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					THE VALUE OF GREEN INFRASTRUCTURE
  FOR URBAN CLIMATE ADAPTATION




                 The Center for Clean Air Policy
                                 February 2011

                                     Josh Foster
                                   Ashley Lowe
                               Steve Winkelman
                                    About CCAP
 Since 1985, CCAP has been a recognized world leader in climate and air quality policy
and is the only independent, non-profit think-tank working exclusively on those issues at
 the local, national and international levels. Headquartered in Washington, D.C., CCAP
  helps policymakers around the world to develop, promote and implement innovative,
  market-based solutions to major climate, air quality and energy problems that balance
 both environmental and economic interests. For more information about CCAP, please
                                    visit www.ccap.org.




                                Acknowledgements
CCAP applauds the vision, leadership, and effort of our ten partners in the Urban Leaders
    Adaptation Initiative: Chicago, King County, Los Angeles, Miami-Dade County,
Milwaukee, Nassau County, New York City, Phoenix, San Francisco, and Toronto. Over
  the last few years we have been impressed with the partners’ commitment to climate
adaptation, progress in adaptation planning, and their development and implementation of
best practices for managing emerging and future climate change impacts. This report was
 made possible by support from the Rockefeller Foundation and the Surdna Foundation.
This report is dedicated to John H. Foster, a pioneer in the economic valuation of
wetlands in Massachusetts in the early 1970s justifying state and later national
wetlands protection laws. Because he asked then about the value of wetlands, we
are able to ask now about how green infrastructure, climate adaptation, and
community resilience are connected.
                                      TABLE OF CONTENTS

EXECUTIVE SUMMARY.......................................................................................................................... II
WHAT IS GREEN INFRASTRUCTURE? ............................................................................................... 3
ECO-ROOFS ................................................................................................................................................ 5
    GREEN ROOFS–ONE SOLUTION, MULTIPLE BENEFITS ............................................................................... 6
      Economic Costs and Benefits of Green Roofs....................................................................................... 8
    WHITE ROOFS–ADAPTING TO THE URBAN HEAT ISLAND EFFECT ............................................................. 9
      Economic Costs and Benefits of White Roofs...................................................................................... 10
    BLUE ROOFS– ADDRESSING WATER MANAGEMENT CHALLENGES .......................................................... 11
      Economic Costs and Benefits of Blue Roofs........................................................................................ 12
    COMPARING PERFORMANCE AND VALUE OF ECO-ROOF TYPES ............................................................... 13
GREEN ALLEYS AND STREETS .......................................................................................................... 14
    GREEN ALLEYS: PERMEABLE PAVEMENT ................................................................................................. 15
    GREEN ALLEYS: DOWNSPOUT DISCONNECTION AND RAIN WATER COLLECTION ................................... 16
    ECONOMIC COSTS AND BENEFITS OF GREEN ALLEYS .............................................................................. 18
    LOW IMPACT DEVELOPMENT ................................................................................................................... 19
URBAN FORESTRY ................................................................................................................................. 21
        Economic Costs and Benefits of Urban Forestry................................................................................ 23
MANAGERIAL, INSTITUTIONAL AND MARKET-BASED APPROACHES TO CLIMATE
RESILIENCE ............................................................................................................................................. 27
    MANAGERIAL APPROACHES...................................................................................................................... 28
    INSTITUTIONAL APPROACHES ................................................................................................................... 29
    MARKET MECHANISMS ............................................................................................................................. 30
CONCLUSIONS: IMPLICATIONS FOR POLICY, RESEARCH AND TECHNICAL
ASSISTANCE ............................................................................................................................................. 31
    ASKING THE RESILIENCE QUESTION ........................................................................................................ 31
    DELIVERING ADAPTIVE SOLUTIONS THROUGH CLIMATE EXTENSION SERVICES...................................... 33
    CLOSING THOUGHTS ON GREEN INFRASTRUCTURE AND RESILIENCE ...................................................... 34
APPENDIX: EXAMPLES OF COMPREHENSIVE GREEN INFRASTRUCTURE STRATEGIES 1
             The Value of Green Infrastructure for Urban Climate Adaptation



EXECUTIVE SUMMARY

In this paper CCAP provides information on the costs and benefits of “green”
infrastructure solutions for bolstering local adaptation to climate change. Pioneering
cities and counties have used green practices to increase community resilience by
planning for, and adapting to, emerging climate change impacts. Generally, resilience
means that communities can better withstand, cope with, manage, and rapidly recover
their stability after a variety of crises. Practices such as green roofs, urban forestry, and
water conservation are familiar to local governments as strategies to enhance
sustainability and quality of life and they are increasingly being seen as best practices in
climate adaptation. These solutions can help build adaptive capacity through planning,
preparing, or reducing climate-related vulnerabilities, but the uncertainty involved in
calculating their economic and social costs and benefits is a barrier to action for local
governments. This report will evaluate the performance and benefits of a selection of
green infrastructure solutions, using their range of technological, managerial,
institutional, and financial innovations as a proxy for their value for climate adaptation.

Over the coming century, climate change scenarios project that urban regions will be
managing extremes of precipitation and temperature, increased storm frequency and
intensity, and sea-level rise. The problems with which urban areas are already coping
may already be indicating–or at least mimicking – that climate change impacts have
begun to occur and are likely to worsen in the future.

Often green approaches are combined with modifications to other traditional “hard”
infrastructures such as expanding storm-sewers and streets or building storm-water
storage tunnels. In recent thinking, portfolios of “green” infrastructure and technologies
have been indentified as ‘best practices’ at the local level when combined with traditional
“grey” infrastructure to achieve greater urban sustainability and resilience. In addition,
green infrastructure is now being recognized for its value as a means for adapting to the
emerging and irreversible impacts of climate change. Consequently, some local
governments have adopted green infrastructure as a hedge against climate change risks,
particularly if the strategies result in multiple other benefits. The discovery of the
multiple benefits of green infrastructure has induced action regardless of the timing,
extent, and rate of climate change impacts. Given the challenges of accurately calculating
the incremental costs and benefits of climate adaptation policies, this report will use the
costs, benefits, and performance of various green infrastructure practices as proxies for
their value to climate adaptation across a range of technological, managerial, institutional,
and financial innovations.

Green infrastructure approaches help to achieve sustainability and resilience goals over a
range of outcomes in addition to climate adaptation. The climate adaptation benefits of
green infrastructure are generally related to their ability to moderate the impacts of
extreme precipitation or temperature. Benefits include better management of storm-water
runoff, lowered incidents of combined storm and sewer overflows (CSOs), water capture
and conservation, flood prevention, storm-surge protection, defense against sea-level rise,


                                              ii
            The Value of Green Infrastructure for Urban Climate Adaptation


accommodation of natural hazards (e.g., relocating out of floodplains), and reduced
ambient temperatures and urban heat island (UHI) effects. The U.S. Environmental
Protection Agency (EPA) has also identified green infrastructure as a contributor to
improved human health and air quality, lower energy demand, reduced capital cost
savings, increased carbon storage, additional wildlife habitat and recreational space, and
even higher land-values of up to 30%.

The value of green infrastructure actions is calculated by comparison to the cost of “hard”
infrastructure alternatives, the value of avoided damages, or market preferences that
enhance value (e.g. property value). Green infrastructure benefits generally can be
divided into five categories of environmental protection:

(1) Land-value,
(2) Quality of life,
(3) Public health,
(4) Hazard mitigation, and
(5) Regulatory compliance.

Examples of “green” infrastructure and technological practices include green, blue, and
white roofs; hard and soft permeable surfaces; green alleys and streets; urban forestry;
green open spaces such as parks and wetlands; and adapting buildings to better cope with
floods and coastal storm surges.

Green technologies and infrastructure solutions are often implemented with a single goal
in mind, such as managing storm-water or reducing local ambient heat, and the costs and
benefits are often evaluated in the same way. However, the full net-benefit of green
infrastructure development can only be realized by a comprehensive accounting of their
multiple benefits. For example, trees filter water, slow runoff, cool local and regional
urban heat effects and clean air. Additionally, some adaptation practices provide co-
benefits to climate mitigation goals by helping to reduce greenhouse gas emissions. For
example, trees absorb and store carbon and can provide shade that reduces man-made
cooling needs and hence electricity demand.

Application of green infrastructure approaches range in scale from individual buildings,
lots, and neighborhoods to entire cities and metro regions and the benefits range in scale
accordingly. Green infrastructure can be implemented via large centralized public
“macro” projects or smaller decentralized “micro” applications on private property.
Therefore, the benefits of green infrastructure can be measured at the building or site
level such that the individual owners reap the private benefits or, if spread across many
private owners, the benefits can be aggregated to an entire community, city, county,
region, or even nation. Community implementation of green infrastructure particularly
helps local governments to achieve environmental, sustainability, and adaptation goals
within their jurisdictions.

Depending on circumstances and motivations, CCAP Urban Leaders partners and other
pioneering communities have embraced the application of green infrastructure and



                                            iii
            The Value of Green Infrastructure for Urban Climate Adaptation


technologies as a means to prepare for and adapt to climate impacts in addition to a path
to environmental sustainability. As discussed throughout this report, cities have
incentivized green infrastructure projects by 1) showing evidence of upfront or life-cycle
cost savings when compared to alternatives for both public and private projects, 2)
providing direct financial incentives to property owners for green infrastructure
installations; 3) instituting laws, regulations, and local ordinances requiring
implementation of green infrastructure on private property, or 4) mandating that public
projects incorporate green infrastructure to demonstrate viability and value (e.g., street
tree planting, green modifications to roads, green-roofs on public buildings).

Select examples of green infrastructure costs, performance, and benefits:

   Cities
       Green alleys or streets, rain barrels, and tree planting are estimated to be 3-6 times
       more effective in managing storm-water per $1000 invested than conventional
       methods. Portland invested $8 million in green infrastructure to save $250
       million in hard infrastructure costs. A single green infrastructure sewer
       rehabilitation project saved $63 million, not counting other benefits associated
       with green practices such as cleaner air and groundwater recharge benefits.
       Portland’s Green Street projects retain and infiltrate about 43 million gallons of
       water per year and have the potential to manage nearly 8 billion gallons, or 40%
       of Portland’s runoff annually. Portland estimated that downspout disconnection
       alone would lead to a reduction in local peak CSO volume of 20%.

       New York City’s 2010 Green Infrastructure Plan aims to reduce the city’s sewer
       management costs by $2.4 billion over 20 years. The plan estimates that every
       fully vegetated acre of green infrastructure would provide total annual benefits of
       $8,522 in reduced energy demand, $166 in reduced CO2 emissions, $1,044 in
       improved air quality, and $4,725 in increased property value. It estimates that the
       city can reduce CSO volumes by 2 billion gallons by 2030, using green practices
       at a total cost of $1.5 billion less than traditional methods.

       Philadelphia has been using policies and demonstration projects throughout the
       city since 2006 to help promote green infrastructure in planning and development.
       Resulting in drastically reduced CSOs, improved compliance with federal water
       regulations, and savings of approximately $170 million.

   Eco-roofs:
      The life-cycle, net present value of green roofs has been estimated to be as much
      as 40% higher than a conventional roof from storm-water management, reduced
      electricity costs, and air-quality benefits. A sampling of studies shows energy
      savings from green roofs at 15-45% of annual energy consumption—mainly from
      lower cooling costs. Cool or white roofs can save up 65%.




                                             iv
        The Value of Green Infrastructure for Urban Climate Adaptation


   Washington, DC has estimated that installation of green-roofs on most eligible
   buildings could yield a 6-15% reduction in the number of CSOs into local rivers,
   with CSO water volume reductions of up to 26%

   Toronto estimated that installation of green-roofs city-wide could save an initial
   $313,100,000 and $37,130,000 annually.

   A study found that retrofitting 80% of air-conditioned buildings in the United
   States with white roofs would save $735 million annually in reduced energy
   consumption achieving an emissions reduction equivalent to removing 1.2 million
   cars from use.

   A typical blue roof can store about 50% of the water that falls on it annually. One
   inch of rain falling on a 1000 square feet of roof generates 623 gallons of water
   for harvest. Treating 1 million gallons of rain water instead of reusing it saves
   955 – 1911 kWh of electricity.

Permeable and reflective pavement:
   Permeable pavement can reduce storm-runoff volume by 70-90%, similar to a
   meadow or forest.

   A study in Los Angeles showed that increasing pavement reflectivity by 10-35%
   could produce a 0.8°C decrease in UHI temperature and an estimated savings of
   $90 million per year from lower energy use and reduced ozone levels.

Urban Trees:
   Studies have shown that the net economic benefits of mature urban trees range
   from $30-90 per year for each tree, accounting for all potential benefits with an
   ROR of $1.50 to $3.00 for every dollar invested

   A 20-percent tree canopy over a house results in annual cooling savings of 8 to
   18% and annual heating savings of 2 to 8%

   The value of street trees in Washington, DC are estimated at nearly $10.7 million
   annually for all benefits

   In Houston, Texas trees provide $1.3 billion in stormwater benefits (based on
   $0.66 /cubic foot of storage)

   The value from urban forestry in Chicago totals $2.3 billion with total carbon
   sequestration rate of 25,200 tons/year equivalent valued $14.8 million/year

   In 2005, total carbon storage in urban trees in the US was approximately 700
   million tons with net rate sequestration estimated at around 24 million tons per
   year (88.5 million tons CO2equivalent).




                                         v
            The Value of Green Infrastructure for Urban Climate Adaptation


       A study in Manchester, England found that adding 10% green cover in high
       density urban areas and town centers under future climate change projections
       would keep surface temperatures below local baseline historical levels except
       under conditions of high emissions

       Studies have found general increases of up to 37% in residential property values
       associated with the presence of trees and vegetation on a property

   Wetlands
     Building a wastewater treatment system using constructed wetlands costs about
     $5.00 per gallon of capacity compared to roughly $10.00 per gallon of capacity
     for a conventional advanced treatment facility

   Zoning
      A community in Canada estimated that building more flood control infrastructure
      to manage probable future climate change impacts would save $10 million in
      avoided flood damages while rezoning alone would save $155 million.


Climate Extension
Although local governments and communities are using green infrastructure to achieve a
variety of environmental and economic goals, including resilience to climate change,
application of green infrastructure solutions are not yet widespread as adaptation best
practices. Many communities either are unaware of the benefits of green infrastructure to
begin with or believe it’s more expensive or difficult to implement than traditional grey
approaches. Meanwhile, communities that have embraced green infrastructure may not
have connected it with adapting to climate change, or if they have, they may not possess
the necessary capacity, know-how, or resources to plan and implement solutions. One
solution to these barriers of awareness, willingness, and capacity is climate extension.

Climate extension would be a means to customize and deliver adaptation information and
to provide technical assistance and capacity to meet specific local adaptation needs.
Practical advice connecting green infrastructure with climate adaptation could be brought
to bear from university, non-profit, or federal and state government “climate extension
specialists” embedded in local communities. Climate extension specialists could provide
technical assistance to both local governments and property owners on practices
highlighted in this report.


Asking the Climate Question
When implementing green infrastructure and technology solutions to achieve
environmental and sustainability goals, “asking the resilience question” means that local
governments and property owners seek to understand the additional benefits that these
practices may have for adapting to climate change and for building resilient communities.




                                           vi
             The Value of Green Infrastructure for Urban Climate Adaptation


At the intersection of sustainability, smart growth, and climate adaptation is a desire for
more resilient communities that are less vulnerable to natural and human induced hazards
and disasters. Diversity, flexibility, sustainability, adaptability, self-organization, and the
ability to evolve and learn are seen as key system attributes of community resilience. In
the face of climate change, adaptive capacity is seen as encompassing resilience focusing
more comprehensively on planning, preparing, and implementing adaptive solutions.
“Asking the resilience question”—means that local planning and building decisions need
to incorporate how to prepare for and manage impacts from climate change and weather
extremes—essentially “mainstreaming” resilience by enhancing adaptive capacity.




                                              vii
               The Value of Green Infrastructure for Urban Climate Adaptation




    THE VALUE OF GREEN INFRASTRUCTURE
      FOR URBAN CLIMATE ADAPTATION
          “Urban systems provide ideal laboratories for understanding resiliency and for
          developing dual-use technologies, practices, and systems that provide value even
                                   if no negative events occur.”1

Over the coming century, climate change scenarios project that urban regions will be
expected to manage extremes of precipitation and temperature, increased storm frequency
and intensity, and sea-level rise. Increases in problems with which urban areas are
already coping may be indicating–or at least mimicking – that climate change impacts are
already occurring and are likely to worsen in the future.2 In practice, these impacts will
mean coping with:

     •   Longer and hotter heat waves
     •   Increased urban heat island (UHI) impacts such as heat related illness and higher
         cooling demand and costs
     •   More damaging storms and storm surges
     •   Greater river flooding
     •   Increased frequency and intensity of combined sewer overflows (CSOs)
     •   More intense and extended duration of droughts
     •   Longer water supply shortages, and
     •   Declines in local ecosystem services, such as the loss of coastal wetlands that
         buffer communities against hurricanes.

The associated impacts on buildings, water and transportation infrastructure, emergency
preparedness, planning, quality of life, and effective management of these stresses are
only now being considered. For example, among CCAPs Urban Leaders partners:

     Chicago expects an increase in days at or above 90°F from 15 days to 66 days per
     year under projected high rates of greenhouse gas emissions and an additional 30
     days over 100°F. Overall, heat waves are projected to be longer, more frequent, and
     more intense with associated increases on public health impacts, including mortality.
     The frequency of rainfall events delivering more than 2.5 inches in 24 hours are also
     projected to increase, accompanied by associated changes in flood risks and the need
     for improved stormwater management.3


1
  Brad Allenby and Jonathan Fink, “Toward Inherently Secure and Resilient Societies” (12 August 2005) Vol. 309
SCIENCE MAGAZINE, pages 1034-36 (American Academy for the Advancement of Science)
2
  EPA Reducing Urban Heat Islands: Compendium of Strategies (October 2008): Urban Heat Island Basics
<http://www.epa.gov/heatisld/resources/compendium.htm>
3
  Chicago Climate Change Action Plan-Climate Change and Chicago: Projections and Potential Impacts, Executive
Summary (May 18, 2008). Convening Lead Authors: Katharine Hayhoe, Texas Tech University; Donald Wuebbles,
University of Illinois at Urbana-Champaign: http://www.chicagoclimateaction.org/pages/research___reports/8.php


                                                        1
                 The Value of Green Infrastructure for Urban Climate Adaptation


     In Toronto, during particularly intense rainfall in August 2005, a storm washed out
     part of Finch Avenue and caused flash flooding to creeks, rivers and ravines, eroding
     stream-banks and damaging trees and parks. More than 4,200 basements were
     flooded. The damage to public and private property was estimated at $400-500
     million – the most expensive storm in Toronto’s history. The Finch Avenue washout
     alone cost $40 million to repair. Although this specific event cannot be attributed
     directly to climate change, Toronto is preparing for more of these kinds of storms as
     climate change threatens to increase the frequency of intense rain events.4

     As a low-lying coastal community, Miami-Dade County is particularly vulnerable to
     the potential impacts of sea-level rise, higher storm surge, and more frequent and
     intense hurricanes. According to a recent study, Miami currently is ranked first out of
     20 cities in the world in total assets exposed to coastal flooding during a 1 in 100 year
     storm surge. Miami’s current exposed asset value is estimated at over $416 billion,
     and this is projected to increase to over $3.5 trillion by the 2070s.5


Characteristics of a resilient urban system are its ability to bounce back from impacts
which may include elements of flexibility, diversity, sustainability, adaptability, self-
organization, self-sufficiency, and learning.6 However, community resilience and climate
adaptation are difficult to assign value, given uncertainties about future climate impacts
and the subsequent difficulty in knowing when a community is adequately “adapted.”
Multiple goal, no-regrets policies centered on “green-infrastructure” can offer
measureable benefits regardless of how climate changes.

In recent thinking, when combined with conventional “grey” infrastructure development
activities, portfolios of “green” technologies and infrastructure have been indentified as
‘best practices’ at the local level for achieving greater urban sustainability and resilience.7
In addition, green infrastructure is now being recognized for its value as a means for
adapting to the emerging and irreversible impacts of climate change.8,9 Consequently,


4
  Ahead of the Storm: Preparing Toronto for Climate Change, Development of a Climate Change Adaptation Strategy,
REPORT, April 18, 2008: http://www.toronto.ca/teo/adaptation.htm
5
  Climate Change Advisory Task Force (CCATF) Initial Recommendations (April 2008)
http://www.miamidade.gov/derm/climatechange/taskforce.asp
6
  Richard Klein, Robert Nichols, Frank Thomalla, “Resilience to natural hazards: How useful is this concept?”
Environmental Hazards 5 (2003) 35-45 <http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VPC-
4CBW8SR-
1&_user=10&_coverDate=12%2F31%2F2003&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_doca
nchor=&view=c&_searchStrId=1580151226&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0
&_userid=10&md5=65767ac9a548f79b3e7ad867eee1dac6&searchtype=a>
7
  For purposes of this report: “grey” infrastructure are conventional storage structures (reservoirs, detention ponds) and
conveyances (pipes, canals) used to manage drinking, sewer, or storm water usually constructed of concrete or metal;
also including streets, roads, bridges, and buildings that do no incorporate technologies intended to achieve
environmental goals. “Green Infrastructure” are technologies implemented to achieve specific environmental goals
typically using natural vegetated materials but also innovative “grey” materials (e.g. permeable pavement, white roofs)
8
  Green Infrastructure (GI) practices, particularly for storm-water management, are considered synonymous with Low
Impact Development (LID), Sustainable Urban Drainage Systems (SUDS), Stormwater Source Controls (SSCs), and
Best Management Practices (BMPs). This report will collectively refer to these practices as “green infrastructure.”
(“NYC Green Infrastructure Plan: A Sustainable Strategy for Clean Waterways” (Department of Environmental


                                                            2
                The Value of Green Infrastructure for Urban Climate Adaptation


some local governments have adopted green infrastructure as a hedge against climate
change risks, particularly if it results in multiple other benefits. The identification of the
multiple benefits of green infrastructure has induced action regardless of the timing,
extent, and rate of climate change. Given the challenge of accurately calculating the
incremental costs and benefits of climate adaptation policies, this paper will use the costs,
benefits, and performance of various green infrastructure practices as proxies for their
value to climate adaptation.



What is Green Infrastructure?
Originally, “green” infrastructure was identified with parkland, forests, wetlands,
greenbelts, or floodways in and around cities that provided improved quality of life or
“ecosystem services” such as water filtration and flood control.10 Now, green
infrastructure is more often related to environmental or sustainability goals that cities are
trying to achieve through a mix of natural approaches. Examples of “green”
infrastructure and technological practices include green, blue, and white roofs; hard and
soft permeable surfaces; green alleys and streets; urban forestry; green open spaces such
as parks and wetlands; and adapting buildings to better cope with floods and coastal
storm surges.11

Conversely, “Gray” infrastructure refers to more traditional approaches to dealing with
impacts, including building more wastewater treatment facilities to deal with increases in
runoff from more intense precipitation events. “Gray” infrastructure approaches may
compliment green infrastructure approaches in helping communities to develop climate
resilience. For instance, innovations such as permeable pavement could be considered a
hybrid of green and gray infrastructure. Sometimes, non-structural approaches to
implementing green infrastructure are referred to as “soft” approaches, while other times
“soft” refers to institutional means of changing behavior such as regulations or market
incentives.

Applications of these green infrastructure approaches range in scale from individual
buildings, lots, and neighborhoods to entire cities and metro regions. Green
infrastructure strategies can be implemented via large, centralized public “macro”
projects or through smaller, decentralized “micro” applications on private property.12

Protection (September 2010))
www.nyc.gov/html/dep/pdf/green_infrastructure/NYCGreenInfrastructurePlan_ExecutiveSummary.pdf)
(PlaNYC, Sustainable Stormwater Management Plan 2008 (October 2008) City of New York)
http://www.nyc.gov/html/planyc2030/html/stormwater/stormwater.shtml)
9
  (PlaNYC Stormwater (2008));(Natural Security, American Rivers (2009)) <http://www.americanrivers.org/our-
work/global-warming-and-rivers/infrastructure/natural-security.html>);(“Your Home in a Change Climate: Retrofitting
Existing Homes for Climate Change Impacts,” London Climate Change Partnership (February 2008) <
www.london.gov.uk/trccg/docs/pub1.pdf>);(EPA Managing Wet Weather with Green Infrastructure, Action Strategy
2008, www.epa.gov/npdes/pubs/gi_action_strategy.pdf)
10
   Edward McMahon, “Looking Around: Green Infrastructure”, Planning Commission Journal (Winter 2000)
Burlington, Vermont, No. 37
11
   This report will collectively refer to these practices as “green infrastructure.”
12
   PlaNYC Stormwater (2008)


                                                        3
                The Value of Green Infrastructure for Urban Climate Adaptation


Therefore, the benefits of green infrastructure can be measured at the building or site
level such that the individual owners reap the private benefits or, if spread across many
private owners, the benefits can be aggregated to an entire community, city, county,
region, or even nation. However, to achieve these benefits of scale there must be
coordinated implementation across a broader area involving multiple parties to reach
certain critical levels of participation. Consequently, community-level, rather than
individual-level implementation of green infrastructure particularly helps local
governments to achieve environmental, sustainability, and adaptation goals within their
jurisdictions.

The climate adaptation benefits of green infrastructure are generally related to its ability
to moderate the expected increases in extreme precipitation or temperature. Benefits
include better management of storm-water runoff, lowering incidents of combined storm
and sewer overflows (CSOs), water capture and conservation, flood prevention,
accommodation of natural hazards (e.g., relocating out of floodplains), reduced ambient
temperatures and urban heat island (UHI) effects, and defense against sea level rise (with
potential of storm-surge protection measures). The U.S. Environmental Protection
Agency (EPA) has also identified green infrastructure as a contributor to improving
human health and air quality, lowering energy demand, reducing capital cost savings,
increasing carbon storage, expanding wildlife habitat and recreational space, and even
increasing land-values by up to 30%.13

Given the above benefits, green infrastructure approaches help to achieve sustainability
and resilience goals over a range of outcomes, in addition to climate adaptation. The
value of green infrastructure is calculated by comparing the costs of green practices to
“hard” infrastructure alternatives, the value of avoided damages, or market preferences
that enhance value, like property value.14 Green infrastructure benefits generally can be
divided into five categories of environmental protection:

(1) Land-value,
(2) Quality of life,
(3) Public health,
(4) Hazard mitigation, and
(5) Regulatory compliance.15

Green technologies and infrastructure solutions are often implemented with a single goal
in mind, such as managing storm-water or reducing local ambient heat, and the costs and
benefits are often evaluated in the same way. However, their full net-benefit can only be
realized by a comprehensive accounting of their multiple benefits. For example, trees
filter water, slow runoff, cool local and regional urban heat effects, and clean air.

13
   EPA Wet Weather (2008)
14
   S. Wise et al, Integrating Valuation Methods to Recognize Green Infrastructure's Multiple Benefits, Center for
Neighborhood Technology (CNT), Chicago, April 2010 (http://www.cnt.org/repository/CNT-LID-paper.pdf)
15
   (EPA “Reducing Stormwater Costs through Low Impact Development (LID) Strategies and Practices, December
2007 <http://www.epa.gov/owow/NPS/lid/costs07/documents/reducingstormwatercosts.pdf>);(Natural Security,
American Rivers (2009))


                                                          4
               The Value of Green Infrastructure for Urban Climate Adaptation


Additionally, some adaptation practices provide co-benefits to climate mitigation goals
by helping to reduce greenhouse gas emissions. For example, trees absorb and store
carbon and can provide shade that reduces man-made cooling needs and hence electricity
demand.

Consequently, when implementing green infrastructure and technology solutions to
achieve environmental and sustainability goals, “asking the resilience question” means
that local governments and property owners seek to understand the additional benefits
that these practices may have for adapting to climate change and for building resilient
communities. The following sections explore the costs, performance and benefits of
various types of green infrastructure practices.



Eco-Roofs
In terms of climate adaptation, eco-roofs are generally installed to respond to two
primary climate drivers–extreme precipitation and temperature. There are three main
types of eco-roofs: Green roofs (vegetated), white roofs (cooling), and blue roofs (water
managing). Green, blue, and white roofs have distinct and overlapping benefits
compared to typical “black” roofs meant solely to provide shelter. Communities or
building owners with limited budgets, who are primarily interested in energy savings or
reducing peak energy demand, generally focus on cool roofs. Those who can consider
life-cycle costs and public benefits, and who are interested in broader environmental
impacts (particularly improving storm-water management) may choose to install green
roofs. Sustainability leaders, such as Chicago and New York City, recognize the value
and opportunity for both cool and green roof technologies and are supporting efforts to
encourage both options.16

Eco-roofs are usually established to achieve additional environmental and sustainability
goals, including:

     •   Water conservation
     •   Storm-water runoff and water quality management
     •   Local and regional cooling
     •   Aesthetic value
     •   Electricity savings
     •   Habitat provision for wildlife
     •   Carbon absorption

There are three primary types of eco-roofs: Green roofs, White roofs and blue roofs. The
next sections will describe the properties, costs and benefits associated with each type of
eco-roof.


16
  EPA Reducing Urban Heat Islands: Compendium of Strategies (October 2008): Green Roofs <
http://www.epa.gov/heatisld/resources/compendium.htm>


                                                      5
                The Value of Green Infrastructure for Urban Climate Adaptation



Green Roofs–One Solution, Multiple Benefits
Green (vegetated) roofs are partially or completely covered with plants or trees
appropriate to the local climate which grow in 3-15 inches of soil, sand, or gravel planted
over a waterproof membrane. They also may include additional layers such as root
barriers, drainage nets, or irrigation systems. Vegetation may be planted modularly in
trays for ease of maintenance or on soil spread across the roof. Roofs may need to be
structurally reinforced when built to support the extra weight. Older buildings can be
retrofitted for this purpose unless they have already reinforced for other reasons. Green
roofs can be either intensive (80-100 lbs. per sq. ft.) or extensive (15-50 lbs. per sq. ft.).
Extensive roofs typically have aesthetic goals and are grown on shallower surface
material costing from $6-43 per square foot to install.17 Intensive roofs are installed at
$20-85 per square foot and use deeper soil and hardier plants that better tolerate a variety
of water conditions. Annual
maintenance costs for vegetated
roofs vary greatly depending on
the nature of the roof, climate
conditions, and local labor rates,
but experience shows annual costs
are 2-3% of construction per year
after vegetation has been
established.18 Green roofs also
protect the underlying roofing
material from wind damage, UV
rays, and regulate temperature
impacts by as much as 21°C,
increasing roof life-spans by 2-3
times and achieving associated life
cycle cost savings.19

Green roofs can reduce annual
stormwater run-off by 50-60% on
average, including peak runoff.20
Vegetated roofs control between       Figure 1: Structure of a Green Roof (Source: heatusa.com)
30-90% of the volume and rate of
stormwater runoff, detaining 90% of volume for storms less than one inch and at least
30% for larger storms.21 Intensive roofs are approximately twice as good at runoff
management as extensive roofs. Seasonal and physiological evapotranspiration rates for

17
   A typical flat black roof costs $2.50-3.50 per square foot. The 4 Kinds of Flat Roofs (This Old House Website).
http://www.thisoldhouse.com/toh/article/0,,1110914,00.html
18
   PlaNYC Stormwater (2008)
19
   National Institute of Building Sciences website, Extensive Green Roof – Definition
<http://www.wbdg.org/resources/greenroofs.php>
20
   Green Roof: Final Presentation, Gateway Team, Columbia University Green Roof Project Submission Date (July 26,
2007) <http://community.seas.columbia.edu/cslp/reports/summer07/greenroofGreen_roof_final_pdr.pdf>
21
   RETENTION temporarily holds or slows stormwater releases from a site—primarily to delay peak flows.
DETENTION holds storm-water on-site until it can be released or reused on-site


                                                        6
                The Value of Green Infrastructure for Urban Climate Adaptation


plants also impact effectiveness of runoff control, with summer growing season being
better than winter. Up to 85% of some water nutrient pollutants can be captured by
intensive green roofs once established. These characteristics have tangible benefits for
urban communities. Washington, DC has estimated that installation of green-roofs on
most eligible buildings could yield a 6-15% reduction in the number of combined sewer
overflows into local rivers, with CSO water volume reductions of up to 26%.22
Additionally, in New York City installing one 40-square-foot green roof could result in
810 gallons of stormwater captured per roof per year. If each installation cost $1,000
then a $100,000 dollar investment could lead to over 81,000 gallons of stormwater
captured, according to a recent study by Riverkeepers.23

A green roof can also filter air pollutants, including particulate matter (PM) and gaseous
pollutants such as nitrogen oxide (NOX), sulfur dioxide (SO2), carbon monoxide (CO),
and ground-level ozone (O3). Researchers estimate that a 1,000-square foot green roof
can remove about 40 pounds of PM from the air annually while also producing oxygen
and removing carbon dioxide (CO2). Forty pounds of PM is roughly equivalent to the
annual emissions of 15 passenger cars. The temperature benefits of green roofs extend to
climate change mitigation as well. Vegetation and the growing medium on green roofs
also can store carbon. Modeling has determined that green roofs may reduce building
energy use for electricity consumption by 2 - 6% over conventional roofs, particularly for
summer cooling.24 One study estimated carbon sequestration at 375 grams per square
meter for green roofs. However, because many of the plants are small and the growing
medium layer is relatively thin, green roofs tend not to have as large a carbon storage
capacity as trees or urban forests.25

One of the greatest benefits of green roofs is their ability to combat the urban heat island
effect. Green roofs in some cases reduce surface temperature by 30-60°C and ambient
temperature by 5°C, compared to conventional black roofs. A study in Portland
calculated that a neighborhood with 100% green roofs could reduce heat island effects by
50-90%. Additionally, studies of New York City and Toronto estimate that a 0.4°C
reduction in the regional UHI effect can be achieved with installation of green roofs on
only 50% eligible roofs across the entire city. Similarly, an Environment Canada study
determined that greening 6% of available roof space in Toronto would reduce summer
temperatures by 1°C to 2°C overall.26 In terms of quality of life improvements, the
inclusion of green roofs in a city landscape has been shown to reduce noise pollution by 2
– 8 decibels. 27




22
   PlaNYC Stormwater (2008)
23
   PlaNYC, Water Quality Initiatives website <http://www.nyc.gov/html/planyc2030/html/plan/water_quality-green-
roofs.shtml>
24
   CNT Multiple Benefits (April 2010)
25
   EPA Heat Islands Compendium (October 2008): Green Roofs
26
   Time to Tackle Toronto’s Warming Climate change adaptation options to deal with heat in Toronto, Eva Ligeti,
Clean Air Partnership (2007) <www.cleanairpartnership.org/pdf/time_to_tackle_toronto_warming.pdf>
27
   CNT Multiple Benefits (April 2010)


                                                        7
                 The Value of Green Infrastructure for Urban Climate Adaptation


Economic Costs and Benefits of Green Roofs
The life-cycle costs and benefits of green roofs vary greatly but the net present value to
urban watersheds has been estimated to be 10-14% higher than a conventional roof, even
taking into account the higher maintenance costs of green roofs. Some studies estimate
the value as high as 20-25% more than conventional roofs, based on benefits from storm-
water management and reduced electricity costs, and up to 40% when air-quality benefits
are added. A sampling of studies shows energy savings from green roofs at 15-45% of
annual energy consumption—mainly from lower cooling costs. These figures do not
consider overall financial benefits from extended roof-life, insulating value, reduced
urban heat island effects, local and regional water quality improvements, fewer combined
sewer overflows (CSOs), urban biodiversity, noise dampening, increases in aesthetic and
property values, or from nominal carbon sequestration.28

 Although green roofs are more expensive per square foot to install than conventional
roofs, their multiple benefits make them cost-effective to implement particularly when
aggregated across many installed roofs over an entire urban area. The following table
shows the monetized value of green roofs to the city of Toronto, if they were applied to
100% of eligible roofs.


     TABLE 1: Estimated City-wide Potential Value of Green Roofs in Toronto29,30
 Category of Benefit                                         Initial cost saving            Annual cost saving
 Stormwater                                                          $118,000,000                         -
 Combined Sewer Overflow (CSO)                                        $46,600,000                           $750,000
 Air Quality                                                            -                                 $2,500,000
 Building Energy                                                      $68,700,000                        $21,560,000
 Urban Heat Island                                                     $79,800,000                       $12,320,000
 TOTAL                                                               $313,100,000                        $37,130,000


A University of Michigan study compared the expected costs of conventional roofs with
the cost of a 21,000-square-foot green roof and all its benefits, such as, storm-water
management and improved public health from the NOX absorption. The green roof would
cost $464,000 to install versus $335,000 for a conventional roof in 2006 dollars, a
difference of $129,000. However, over its lifetime, the green roof would save about
$200,000. Nearly two-thirds of these savings would come from reduced energy needs for
28
   PlaNYC Stormwater (2008)
29
   Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto, Ryerson
University (2005) < http://www.toronto.ca/greenroofs/pdf/executivesummary.pdf>;<
http://www.toronto.ca/greenroofs/pdf/fullreport103105.pdf>. Cost savings are relative to standard roofing materials
calculated across multiple categories of benefits (stormwater management, air quality improvements) and also
including discounted life-cycle rates, economies of scale, installation, maintenance, and administrative cost, etc.—see
report for more detailed explanations
30
   This assumes that “100% of available area” includes all flat roofs greater than 3,750 sq. ft. with vegetation covering at
least 75% of the roof. This amount totals 12,000 acres of roof, or 8% of Toronto’s land area.


                                                             8
               The Value of Green Infrastructure for Urban Climate Adaptation


the building.31 In addition, Portland completed a comprehensive cost-benefit analysis of
its current green roof program in 2008, calculating that green roofs provide each private
homeowner, on average, a net benefit of $404,000 over 40 years from avoided storm-
water fees, reduced heating and cooling costs, and longer roof life. Green roofs on public
buildings were estimated to provide a net-benefit of $191,000 from reduced operations &
maintenance costs, avoided storm-water management costs, particulate pollution and
carbon absorption benefits, and habitat amenities.32


Green Roofs – Chicago City Hall 1

In 2001, a 20,300 square-foot green roof was installed atop Chicago’s City Hall as part of
Mayor Daley’s Urban Heat Island Initiative. The roof includes 20,000 plants, shrubs,
grasses, vines, and trees. When compared to an adjacent normal roof, City Hall’s green
roof is nearly 56°C lower—plus benefits include improved air quality, reduced storm-water
runoff of 75% for a 1 inch storm, and energy savings.1

 The city expects annual savings of more
than 9,270 kWH of electricity and nearly
740 BTUs of natural gas for heating. This
amounts to more than 6.3 tons of CO2e
saved, using EIA conversion factors.1
Energy cost savings is estimated at
$3,600-$5,000 annually, increasing with
higher energy prices.1 To date, Chicago
has over 400 green roof projects in various
stages of development with 7 million
square feet of green roofs constructed or
underway (more than all other U.S. cities
combined).                                             Figure 2: Chicago's City Hall Green Roof




White Roofs–Adapting to the Urban Heat Island Effect
The urban heat island effect is caused by the tendency of hard, dark surfaces, such as
roofs and pavement, to be measurably hotter than natural areas. It can raise a city’s
temperatures 2 to 5.5° C on hot summer days. White or cool roofs are generally flat roofs
that have been painted white or are surfaced with some other light or reflective
material—often adding durability while reducing ambient temperatures. Research reveals
that conventional roofs can be 31-55° C hotter than the air on any given day, while cool
roofs tend to stay within 6-11°C of the background temperature. This cooling
performance can lower ambient temperature, mitigate the UHI, and help prevent
31
  EPA Heat Islands Compendium (October 2008): Green Roofs
32
  Cost Benefit Evaluation of Eco-roofs, City of Portand, Oregon (2008) <
http://www.portlandonline.com/BES/index.cfm?a=261053&c=50818>. The net-benefits for the public building do not
include energy cost savings which explains the lower overall figure.


                                                      9
                The Value of Green Infrastructure for Urban Climate Adaptation


mortality during heat waves.33 White vinyl roofs are the most reflective common
material used, reflecting 80% of the sun’s rays compared to only 6% reflection on a
conventional black roof and avoiding 70% of the heat absorption experienced on black
roofs. Some coatings can reach even higher levels of reflectivity.34


Economic Costs and Benefits of White Roofs
The cost of white roofs is comparable to that of conventional roofs, costing between
$0.20 and $6.0 per square foot to install.35 Energy savings from cool roofs result in
monetary savings from reduced cooling costs, varying from 10-70% in total energy use
savings per building. Additionally, reductions in the peak demand for cooling energy
range from 14-38% after installation. A study of 11 US cities determined that the average
net cost savings from reduced energy consumption reached $0.22 per square foot of
installed cool roof per year.36

The reflective benefits of white roofs accrue regionally across urban areas as more white
roofs are added and can be aggregated nationally or even globally. A 2009 study by the
Lawrence Berkeley National Laboratory’s (LBNL) Heat Island Group found that
retrofitting 80% of air-conditioned
buildings in the United States with
white roofs would save $735 million
annually in reduced energy bills while
achieving an emissions reduction
equivalent to removing 1.2 million
cars from the road. Another study by
LBNL in 2010 used global climate
models to determine the cooling
benefit of increasing the reflectivity of
roofs and roadways in large cities. The
study found that increasing the
reflectivity of surfaces in urban areas
with a population of over one million     Figure 3: Creating a white roof is relatively simple
would reduce global heating by 0.4°C
on average. This in turn would offset the heating effect of 1.2 gigatons of CO2 emissions
annually, the equivalent of taking 300 million cars off the road for 20 years.37

A demonstration project for Tucson, Arizona documented how a cool roof reduced
temperatures inside the building and saved more than 400 million Btu annually. A white
elastomeric coating was installed over a 28,000-square foot un-shaded metal roof on one

33
   EPA Heat Islands Compendium (October 2008: Cool Roofs)
34
   Wikipedia website: Cool Roofs <http://en.wikipedia.org/wiki/Cool_roof>
35
   EPA Heat Islands Compendium (October 2008): Cool Roofs
36
   EPA Heat Islands Compendium (October 2008): Cool Roofs
37
   Global Model Confirms: Cool Roofs Can Offset Carbon Dioxide Emissions and Mitigate Global Warming, Press
Release (July 19, 2010), Lawrence Berkeley National Laboratory <http://newscenter.lbl.gov/news-
releases/2010/07/19/cool-roofs-offset-carbon-dioxide-emissions/); (Painting the Town White -- and Green (March
1997), Lawrence Berkeley National Laboratory, http://heatisland.lbl.gov/PUBS/PAINTING/)


                                                       10
                The Value of Green Infrastructure for Urban Climate Adaptation


of the city’s administration buildings. Following the installation, energy savings were
calculated at 50 to 65% of the building’s cooling energy—an avoided energy cost of
nearly $4,000 annually.1


Blue Roofs– Addressing Water Management Challenges
It is estimated that $500 billion is needed to repair and upgrade the current US water
supply, waste water, and storm-water systems, with an additional $500 billion needed to
accommodate climate change impacts.38 These estimates include $63.6 billion to control
CSOs and $42.3 billion for storm-water management.39 In “Natural Security”, American
Rivers identifies green infrastructure as a preferred approach for managing water in the
coming century to cost-effectively and flexibly cope with the impacts of climate change
on communities.40 Blue roof practices are one of the green infrastructure solutions that
address these growing needs.

Similar to a standard green roof, a blue roof slows or stores
storm-water runoff but it accomplishes this by using various
kinds of flow controls that regulate, block, or store water
instead of vegetation. Examples of blue roof technologies
include downspout valves, gutter storage systems and cisterns.
Water can be temporarily stored or harvested for non-potable
uses on-site, and used or reused for landscape or garden
irrigation, direct groundwater recharge via methods like
downspout disconnections and infiltration systems, or
discharged directly into sewer systems at a reduced flow rate
or after peak flow from storms. The captu red water can also
be sprayed directly on the roof to increase the evaporative
cooling effect for the building. The goal is to mimic pre-
construction runoff rates at the site primarily to reduce
overloads on inadequate or aging
local storm-water infrastructure and prevent localized flooding,
potential flood damage, and CSOs. Blue roofs can also help to Figure 4: Weirs at the roof drain inlets
attain Low Impact Development (LID) standards, with              create temporary ponding and more
infiltration systems earning 1 LEED credit and mechanisms to gradual release of water (NYC)
store water for reuse earning 3-4 LEED credits under the
“Water Efficiency” guidelines.41



38
   “Drinking Water Infrastructure Needs Survey and Assessment: Third Report to Congress.” USEPA Office of Water,
2005. “Clean Watersheds Needs Survey 2004: Report to Congress.” USEPA (January 2008)(from David Behar
SFPUC)
39
   CNT Multiple Benefits (April 2010); EPA Clean Watersheds Needs Survey (2008)
<http://water.epa.gov/scitech/datait/databases/cwns/upload/cwns2008rtc.pdf>
40
   (Natural Security, American Rivers, 2009);(Sustainable Water Systems: Step One - Redefining the Nation’s
Infrastructure Challenge. Report of the Aspen Institute’s Dialogue on Sustainable Water Infrastructure in the US. The
Aspen Institute, Energy and Environment Program (May 2009). http://www.aspeninstitute.org/publications/sustainable-
water-systems-step-one-redefining-nations-infrastructure-challenge)
41
   LEED: Leadership in Energy and Environmental Design


                                                        11
               The Value of Green Infrastructure for Urban Climate Adaptation


Economic Costs and Benefits of Blue Roofs
Adding blue roof flow controls adds less than $1 - 4 per square foot in additional or
incremental cost to the design of a new flat roof. Additionally, blue roofs do not require
the expensive structural reinforcement that is required in cases of green roof retrofits.
They also need less maintenance (particularly at start-up), and do not discharge the
nutrients and chemicals that may run off of green roofs. A typical blue roof with storage
capability can store about 50% of the water that falls on it annually.42 One inch of rain
falling on a 1,000 square feet of roof generates 623 gallons of water for harvest. 43

Installing blue roofs can create energy savings and result in emission reductions as well.
Treating 1 million gallons of rain water uses 955 – 1911 kWh of electricity. In
California, the system-wide energy cost to convey, treat, and distribute 1 million gallons
of water is 12,700 kWh, or 8.6 tons CO2.44 By decreasing the amount of water needing
treatment communities can save energy and cut carbon emissions at the same time.
Savings per gallon captured and used will depend on the local market value of water.
Storm-water detention and retention value will also vary locally depending on savings
from local storm-water fees, or more generally from improved local water quality
(including avoided Clean Water Act regulatory fees), or damage avoided from CSOs or
flooding.

Seattle, Washington provides an example of various blue roof practices in action. Their
rain catcher pilot program consists of three different types of rainwater collection
systems:

     1. Tight-line–directs rainwater outflow to a pipe that flows under the yard through
        weep holes in the sidewalk, reducing volumes deposited in the storm drain via the
        curb.

     2. Tight-lined cistern–a cistern at the point of initial outflow that collects water
        during the storm event and releases it slowly into the underground pipes.

     3. Orifice cisterns–include an operable valve which can be opened during the wet
        season, discharging a small amount of water onto an adjacent permeable surface
        such as a lawn or rain garden to slow down flow. It can also be closed to store up
        to 500 gallons of roof runoff, which can be used later for irrigation.

Each cistern cost the city a total of $1000 with $325 of that sum paying for the wholesale
purchase of the cistern and $675 to installation and overhead. Seattle is currently
analyzing the impact of cisterns on the combined sewer system as part of a grant.45


42
   EcoStructure website, “Blue is the New Green” Blog (February 2010) http://www.eco-structure.com/water-
conservation/blue-is-the-new-green.aspx.
43
   CNT Multiple Benefits (April 2010)
44
   CNT Multiple Benefits (April 2010)
45
   Low Impact Design Toolkit, What Will You Do with San Francisco’s Stormwater. San Francisco Public Utility
(SFPUC). Urban Stormwater Planning Charette (September 2007)<sfwater.org/Files/Reports/UWP_toolkit.pdf>


                                                       12
                The Value of Green Infrastructure for Urban Climate Adaptation




                           The Value of Rainwater Harvesting46

•    King Street Center, Seattle, WA: The Center uses rainwater for toilet flushing and
     irrigation. Rainwater from the building’s roof is collected in three 5,400 gallon
     cisterns. The collection and reuse system is able to provide 60% of the annual water
     needed for toilet flushing, conserving approximately 1.4 million gallons of potable
     water each year.

•    Solaire Buiding, New York, NY: Rainwater is collected in a 10,000 gallon cistern
     located in the building’s basement. Collected water is used for toilet flushing and
     make-up water. The system and other measures have decreased potable water use in
     the building by 50%, earning the building New York State’s first-ever tax credit for
     sustainable construction.

• Stephen Epler Hall, Portland State University, Portland, OR: The storm-water
     management system was designed to take rain from the roofs of two buildings and it
     diverted to several “splash boxes” in the public plaza. The water is filtered and
     collected in underground cisterns prior to its reuse for toilet flushing and landscape
     irrigation. The stormwater collection and reuse system conserves approximately
     110,000 gallons of potable water annually, providing a savings of $1,000 each year




Comparing Performance and Value of Eco-roof Types
As illustrated above, each roofing technology exhibits different performance
characteristics and trade offs between overall net benefits and their cost to establish and
maintain. Because they are covered with soil and vegetation, green roofs are generally
more expensive to establish, retrofit, and maintain but may provide a greater variety of
benefits at a better rate of performance and for a longer period of time than any other
kind of roof, thus producing a higher net economic, social, and environmental value. For
example, for an 11,000 square foot surface, a green roof would save roughly $400 per
year in heating costs and $250 per year in cooling costs for a total of $650 per year, while
a white roof would save roughly $200 per year in cooling and does not contribute to
heating cost reductions.47

Blue and white roofs are cheaper to install and upkeep but may only offer single focus
benefits related either to water conservation and runoff control or heat reduction.
However, all three types have value for adapting to climate change and local decision
makers will need to evaluate the merits of each solution in relation to the impacts that

46
 EPA Wet Weather (2008)
47
 Gaffin, S. R., Rosenzweig, C., Eichenbaum-Pikser, J., Khanbilvardi, R. and Susca, T. (2010). “A Temperature and
Seasonal Energy Analysis of Green, White, and Black Roofs” (Con Edison Facility) Columbia University, Center for
Climate Systems Research. New York, NY) http://ccsr.columbia.edu/cig/greenroofs


                                                       13
                  The Value of Green Infrastructure for Urban Climate Adaptation


they want to address. Other characteristics to assess will include comparisons of cost-
benefit analysis, scales of implementation, general acceptability to the community, and
suitability for the local climate. As an example, the following table illustrates the
differences in costs, impacts and other characteristics between green roofs and blue roofs
in New York City.

         TABLE 2: Storm-water Performance and Value of Green and Blue Roofs48

      NYC Relative Cost of Stormwater Control Technologies: Blue and Green Roofs
        Source   Incremental Net Present Lifespan Cost Gallons Cost To                     Annual Cost
       Control      Capital     Value (per    (yrs.)    Per     (per sq Capture             per Gallon
                   Cost (per     sq ft or              Year      ft or   Gallon            (annualized
                   sq. ft. or     unit)                          unit)                     net present
                     unit)                                                                    value)
      Blue Roof          $4.00  $4.00        20        $0.20        1.25  $3.21                   $0.16
      (2-inch
      detention)
      Blue Roof          $4.00  $4.00        20        $0.20        0.62   $6.42                 $0.32
      (1-inch
      detention)
      Green             $24.45 $62.39        40        $1.56        0.47 $133.37                 $3.33
      Roof




Green Alleys and Streets
Alleys in cities are usually public spaces adjacent to private properties that allow for
public access by fire, police, and delivery services and also for management of storm-
water runoff and heat effects around buildings and properties. Urban alleys are
traditionally surfaced with impermeable materials (e.g., asphalt, concrete) with the
objective of achieving rapid storm-water runoff into storm-sewers, in addition to
providing access for vehicles. However, frequent or intense rains combined with
impermeable surfaces can lead to localized flooding, which is expected to be worse under
anticipated climate change conditions. Older infrastructure particularly suffers from
these problems. Alleys surfaced in dark materials or without shade-trees lead to
increased ambient temperatures around buildings and higher energy demand for building
cooling, causing increases in the associated costs to building owners. Higher
temperatures also add to UHI effects and can degrade air-quality. Green alleys can help
manage these impacts.

Green alleys are an example of where several site- or neighborhood- specific green
infrastructure innovations merge, producing multiple benefits and a holistic means to
implement climate adaptation. Green alleys use a number of green infrastructure
practices to achieve stormwater management, heat reduction and energy conservation
goals, including:
48
     Adapted from PlaNYC, Sustainable Stormwater Management Plan 2008 (Table 8, Page 41)




                                                        14
                The Value of Green Infrastructure for Urban Climate Adaptation



•    Permeable and reflective pavements,
•    Rain-gardens (vegetation installed in artificial depressions to capture rainwater),
•    Downspout disconnects and rain-barrels,
•    Tree-planting,
•    Landscaping and bio-swales (artificially contained vegetation),
•    Cisterns,
•    Eco-roofs, and
•    Recycled materials.49

In addition, green alleys can earn LEED credits for their contributions to urban
sustainability. Permeable pavement can earn credits for storm-water water quality
maintenance, UHI reductions, and recycled materials while landscaping can earn water
efficiency credits.50,51 Slower runoff and storm-water capture generally reduces
municipal pumping demand and electricity costs, meeting both mitigation and adaptation
objectives. The following sections will discuss two green alley tools in detail, permeable
pavement and downspout disconnection/rainwater collection.


Green Alleys: Permeable Pavement
Permeable pavement is made out of materials that allow water to soak back into the
ground rather than running over it and into other stormwarter management systems. The
goal of permeable pavement strategies is to produce runoff characteristics in cityscapes
that are similar to those in a meadow or a forest. Studies have shown that permeable
pavement with proper “sub-soiling” (maintenance of a porous layer of soil underneath)
can reduce runoff volume by 70 to 90%.52 Permeable pavement in a typical alley can
infiltrate 3 inches of rainwater from a 1-hour storm with an infrastructure life expectancy
of 30 to 35 years.53 It is typically designed with the capacity to manage a 10-year rain
event within a 24-hour period—a standard that will likely need to be adjusted for to
account for projected increases in frequency and intensity of storms in the future.
Research also indicates that permeable pavement offers other benefits to cities, including
reducing the need for road salt application on streets in the winter by as much as 75% and
reducing road noise by 10 decibels.54,55

49
   Chicago Green Alley Handbook
<http://www.cityofchicago.org/city/en/depts/cdot/provdrs/alley/svcs/green_alleys.html>
<http://www.cityofchicago.org/content/dam/city/depts/cdot/Green_Alley_Handbook_2010.pdf>
50
   National Ready Mixed Concrete Association (NRMCA) website, Using Pervious Concrete to Achieve LEED Points
<http://www.perviouspavement.org/benefits_LEEDcredit.htm>
51
   (Norbert Delatte, “Sustainability Benefits of Pervious Concrete Pavement” (2010)(Cleveland State University) and
Stuart Schwartz (University of Maryland-Baltimore Campus)<www.claisse.info/2010%20papers/p14.pdf>));(Chicago
Green Alley Handbook).
52
   “Greening Gets Down and Dirty,” Timothy B. Wheeler, Baltimore Sun (August 20, 2010)<
http://articles.baltimoresun.com/2010-08-20/features/bs-gr-subsoiling-20100820_1_polluted-runoff-storm-drains-
storm-water-pollution>
53
   Rooftops to Rivers (2006) NRDC
54
   CNT Multiple Benefits (April 2010)
55
   Effective Curve Number and Hydrologic Design of Pervious Concrete-Water Systems; Stuart Schwartz (University of
Maryland-Baltimore Campus), Journal of Hydrologic Engineering, ASCE (June 2010)<
http://cedb.asce.org/cgi/WWWdisplay.cgi?264283>


                                                       15
               The Value of Green Infrastructure for Urban Climate Adaptation



In terms of the effects on mitigating the urban heat island effect, permeable pavement
tends to be cooler because of its higher reflectivity, lower capacity for absorbing heat,
and greater evaporative capacity. Dark pavements absorb 65 to 90% of the sun’s heat
while the more reflective permeable pavement absorbs only 25%. Consequently, each
10% increase in total reflective surface present in an urban area lowers the UHI surface
temperature by 4°C. A study in Los Angeles showed that by increasing pavement
reflectivity alone by 10 to 35% across the city could lead to a 0.8°C decrease in UHI
temperature and an estimated savings of $90 million per year from lower energy use and
reduced ozone levels. Reduced pavement area and natural vegetation in Davis, CA
helped reduce home energy bills by 33 to 50% compared to surrounding
neighborhoods.56 Extrapolating to the global potential for energy savings and emission
reductions, a 2007 paper estimated that increasing pavement reflectivity in cities
worldwide to an average of 35 to 39% could result in global CO2 reductions worth about
$400 billion.57


Green Alleys: Downspout Disconnection and Rain Water Collection
Another method of controlling rainwater is to disconnect downspouts from homes and
commercial buildings that once directed water into existing stormwater management
systems, often resulting in CSOs when the systems are overwhelmed by intense rainfall.
The downspouts are then reconnected to a collection or slow dispersion system, such as a
cistern (for storage) or a rain garden (for slow dispersion). The aggregate impact of these
measures reduces the
load on existing sewer
systems and provides
water conservation
benefits to the city.

Downspout
disconnections cost
about $2,000 per
household for a full
professional
installation including
new gutters, rain-
barrels, and
redirection of water to
landscaping, but a
rain-barrels can be     Figure 5: (Left) A gutter downspout connected to the storm drain system. (Right) A
purchased for as little disconnected downspout using a rain barrel to collect stormwater for a rain garden
as $15.58
56
   Ed MacMullan, Presentation: “Assessing Low Impact Developments Using a Benefit-Cost Approach,”
ECONorthwest, 2nd Annual Low Impact Development Conference (March 12-14, 2007)
<http://www.econw.com/reports/Low-Impact-Development_Benefit-Cost.pdf>
57
   EPA Heat Islands Compendium (October 2008): Cool Pavements
58
   Low Impact Design Toolkit (2007) SFPUC


                                                      16
                 The Value of Green Infrastructure for Urban Climate Adaptation


Disconnection costs around $0.01 per gallon of stormwater that is permanently removed
from the sewer system. One study noted that if 80% of a neighborhood participated in
downspout disconnections, the community would achieve a 30% reduction in runoff from
the peak flow of a “1-year” storm. Homeowner rain-garden installation could achieve an
additional reduction of 4 to 7%. The study also estimated that downspout disconnection
alone could lead to a reduction in local peak CSO volume of 20%.59

Portland’s Cornerstone Project for reducing CSOs provides voluntary participants $53
per disconnection or pays for a contractor to do the work. Community groups earn $13
for each downspout they disconnect. The program currently has 49,000 homeowners
participating, achieving about 4,400 disconnections per year from 1995 to 2006, and has
removed approximately 1.5 billion gallons of stormwater per year from the combined
sewer system.

The table below illustrates the stormwater reduction benefits of various green alley
practices:

                     TABLE 3: Stormwater Removal Methods Comparison

                          Stormwater                 Average Peak         Average
                          Control Method             Flow (%              Peak Lag
                                                     Removed)             Time
                                                                          (Minutes)
                          48" Soil                                     85          615
                          Bioretention60
                          30" Soil                       82                                  92
                          Bioretention
                          Constructed                    81                                315
                          Wetlands
                          Constructed                    81                                424
                          Retention Pond
                          Porous                         68                                790
                          Pavement
                          Surface Sand                   59                                204
                          Filter
                          Bioswale:                      48                                  19
                          Vegetated
                          Bioswale:               No Data                                    19
                          Treebox Filter
                          Annual Report 2007, University of New
                          Hampshire Stormwater Center; Durham NH



59
  Rooftops to Rivers (2006) NRDC
60
  Soil bio-retention indicates water passed through soil, organic matter, and plant roots where it is absorbed, held, or
filtered.


                                                            17
               The Value of Green Infrastructure for Urban Climate Adaptation


Chicago: A Pioneer of Green Alleys and Streets61
Chicago has 1,900 miles of public alleys with over 3,500 acres of paved surfaces. In
2007, 30 green alleys with permeable pavement and reflective concrete had been
installed, along with over 200 catch-basins across the city. Landscape ordinances
encouraged tree planting and installation in alleys of natural landscaping, rain-gardens
(i.e., vegetation in artificial depressions) and bio-swales (i.e., artificially contained
vegetation). Green alley design also encouraged homeowner involvement in
disconnecting of rain-gutter downspouts from the sewer system, addition of rain-barrels
                                                    to capture rooftop runoff, and backup
                                                    power supplies to sump pumps in
                                                    basements. Simultaneously, building
                                                    owners were encouraged to install green
                                                    roofs.

                                                   The goal of these measures was to slow
                                                  the rate of storm-water runoff onsite and
                                                  through alleys, allowing water to soak
                                                  into the surrounding neighborhoods
                                                  more naturally thus avoiding localized
                                                  basement and surface street flooding and
                                                  to support the capacity of aging
Figure 6: A green alley is installed in Chicago   infrastructure to handle extreme
                                                  precipitation events. In 2004, Chicago
provided residents 400 rain-barrels at a cost of $40,000 with the potential to avoid
760,000 gallons of stormwater per year.


Economic Costs and Benefits of Green Alleys
Green alleys or streets, rain barrels, and tree planting are estimated to be 3 to 6 times
more effective in managing storm-water per $1,000 invested than conventional
methods.62 The cost estimates vary depending on the type of technology deployed. Rain
garden or bioretention retrofits range from $2.28 to $7.13 per gallon of storm-water
managed and permeable parking lots cost around $5.50 per gallon. Higher cost options
are curb extension swales, which cost around $10.86 per gallon, and permeable sidewalk
installations, which cost around $11.24 per gallon.63 The installed cost for permeable
pavement in green alleys is $0.10 to $6.00 per square foot with service life of 7 to 35


61
    Chicago Green Alley Handbook;
Chicago’s Sustainable Streets Pilot Project (PPT)
http://www.epa.gov/heatisld/resources/pdf/5-Chicago-SustainableStreetsPilotProject-Attarian-Chicago.pdf
Chicago’s Sustainable Streets Pilot Project (TEXT)
Projecthttp://www.epa.gov/heatisld/resources/transcripts/28Jan2010-Attarian.pdf
62
   House Committee on Transportation and Infrastructure, Hearing, Sustainable Wastewater Management (February 4,
2009)< http://transportation.house.gov/hearings/hearingDetail.aspx?NewsID=805>
63
   Illinois Environmental Protection Agency recommendations as required by Public Act 96-26, The Illinois Green
Infrastructure for Clean Water Act of 2009 (June 30, 2010)< http://www.epa.state.il.us/green-
infrastructure/docs/public-act-recommendations.pdf>


                                                       18
                The Value of Green Infrastructure for Urban Climate Adaptation


years, depending on material and maintenance.                   The following table illustrates the costs
of various green alley practices.

                          TABLE 4: Green Alley Techniques and Costs

                              Green Alley                    Cost per unit to
                              Technique                      install
                              Tree planting                  $50 - $500 per tree
                                                             $0.10 - $5 per sq.
                              Native Landscaping             ft.
                              Rain Garden                    $3 - $6 per sq. ft.
                              Rain Barrel                    $10 - $500064
                              Permeable
                              Pavement                       $3 - $15 per sq. ft.
                              Green Roof                     $10 - 30 per sq. ft.
                                                             $0.7 - $0.14 per sq
                              Natural Detention              ft.
                                                             $8 - $30 per linear
                              Bio-swales                     ft.


However, the economic benefits of installing green alley infrastructure outweigh the costs
in many cases. For example, Portland installed vegetated bio-swales in one street project
over a two-week period at a cost of $15,000. These vegetated curb extensions reduced
peak flow from a 25-year storm event (2 inches in 6 hours) by 88%, protecting local
basements from flooding and reducing total flow into local sewers by 85%.65 For
comparison, the average national insurance claim for flooded basements is $3,000 to
$5,000 per basement.66 Avoiding basement flooding from one storm for just three homes
justifies this investment. For an idea of potential savings, remember that Toronto’s Finch
Avenue storm event caused over 4,000 flooded basements and $500 million in damage.


Low Impact Development67
An EPA study compared 17 local cases of using low impact development for storm-water
management versus conventional options, holding performance equal. The green options
showed cost advantages of 15 to 80% across all cases, and the results only accounted for
the water quality benefits.68 A developer that used Low Impact Development techniques

64
 A $5000 cost for a rain-barrel accounts for a detention system across an entire property (e.g. installation
of new gutter systems, rain-gardens, sewer connections, and potentially roof and subsurface cisterns)
65
  Rooftops to Rivers (2006) NRDC
66
  Avoiding Basement Flooding, Canadian Housing and Mortgage Corporation (2010) <http://www.cmhc-
schl.gc.ca/en/co/maho/gemare/gemare_002.cfm>
67
   It was noted earlier that LID and GI are synonymous for purposes of this paper. In this section, LID shows an
integrated way to implement and value GI
68
    EPA Managing Wet Weather with Green Infrastructure website: Philadelphia Case
<http://www.epa.gov/owow/nps/lid/costs07/factsheet.html><http://cfpub.epa.gov/npdes/greeninfrastructure/gicasestudi
es_specific.cfm?case_id=62>


                                                        19
               The Value of Green Infrastructure for Urban Climate Adaptation


like those used in green alleys in residential subdivisions sold lots for $3,000 more than
lots in competing areas that did not use LID. Replacing curbs, gutters, and storm sewers
with roadside bio-swales in a residential subdivision could save a developer $70,000 per
mile, or $800 per residence. In Los Angeles County it was estimated that while LID
stormwater controls would cost $2.8-$7.4 billion, they would deliver benefits of $5.6-$18
billion.

Using LID throughout a watershed that reduces downstream flooding can result in
economic benefits of $54 to $343 per developed acre.69 For an example of the costs of
LID, Seattle has developed flexible and adaptable natural drainage systems to manage
storm-water. The 72-acre Viewlands Cascade project used “vegetated cells” to reduce
storm-runoff by 75 to 80% and peak flow rates by 60% with top performance in small
rain events. The project used green infrastructure practices including a curving street,
vegetated swales, and additional plantings, resulting in a 99% reduction of monitored
surface runoff at a cost of $850,000 (or $3 to $5 per square foot).70



                                 Green Values Calculators71
The Center for Neighborhood Technology (CNT) in Chicago has developed several
storm-water management tools. The National Green Values Calculator helps users
compare costs, benefits, and performance of green infrastructure and Low Impact
Development across neighborhoods when compared to conventional infrastructure. The
                              tool then recommends BMPs primarily to reduce
                              impermeable surfaces, and increase capture and infiltration
                              of storm-water. The Green Values Stormwater Calculator
                              allows users to generate rough values for hydrologic
                              outputs and financial benefits for green storm-water
                              practices on their properties.
                              Various green interventions can be entered into the tool,
                              including downspout disconnections, permeable pavement,
                              green roofs, tree cover, and drainage swales. Users then
                              enter associated parameters including lot and roof size,
                              number of trees, square feet of permeable pavement,
                              average slope and soil type, etc. The tool then calculates
volumes for lot and site improvements for storm-water detention, annual discharge,
reductions in peak flow, and ground-water recharge when compared to no improvements.
The final output shows reduction in life-cycle costs and increase in monetary benefits.
The Green Stormwater Ordinance Compliance Calculator helps user evaluate and comply
with stormwater BMPs for regulated developments in Chicago.




69
   Ed MacMullan, Presentation: Low Impact Development (2007)
70
   Low Impact Design Toolkit (2007) SFPUC
71
   Green Values® Stormwater Toolbox website & calculator <greenvalues.cnt.org>


                                                    20
                    The Value of Green Infrastructure for Urban Climate Adaptation


    Urban Forestry
    Planting and maintaining trees in urban settings is considered a quintessential green
    infrastructure practice with multiple benefits for resilience, adaptation, and even climate
    mitigation. The benefits of urban forestry extend from individual neighborhood trees to
    widely distributed urban forests. As noted earlier, trees contribute to adaptation by
    intercepting and filtering storm-water runoff to prevent flooding and improve water
    quality, absorbing pollutants to clean the air, providing wind-breaks to protect buildings
    from wind damage, and regulating heat island effects through shading and evaporation.
    Simultaneously, trees contribute to mitigation by lowering cooling demand for electricity
    and directly sequestering carbon. Trees provide wildlife habitat and ecosystem services,
    and have been shown to increase property values. For centuries they have contributed to
    overall urban quality of life. Dead trees even can be recycled into mulch.

    Urban forestry programs establish trees in public spaces such as parks, along streets and
    alleys, or in any available open areas that local governments manage (along stream right-
    of-ways, around public buildings, or in city-owned vacant lots). Urban forestry can
    extend to green-belts around cities that buffer waterways and regulate development, and
    even to acquisition and management of lands to preserve urban watersheds so that
    drinking water supply and quality is protected. Local ordinances often guide property
    owners’ responsibilities for trees as a private and public good.

    Urban forestry delivers a range of stormwater and UHI benefits to communities. A
    typical medium-sized tree can intercept as much as 2,380 gallons of rainfall per year.72
    During the summer, with trees in full leaf, evergreens and conifers in Sacramento, CA
    were found to intercept over 35% of the rainfall that hit them during smaller rainfall
    events. Trees reduce runoff and erosion from storms by about 7% and reduce the need


                     Trees slow and reduce stormwater runoff–improving
                         and protecting the quality of drinking water.1

•     In Houston, TX trees in the provide $1.3 billion in stormwater benefits (based on $0.66
      /cubic foot of storage)

•     In Austin, TX trees provide $122 million in stormwater benefits (based on a national
      average of $2/cubic foot of storage)


•     In Atlanta, GA trees provide $833 million in stormwater benefits (based on a national
      average of $2/cubic foot of storage)



    72
       Fact Sheet #4 website: Control Stormwater Runoff with Trees, Watershed Forestry Resource Guide, A Partnership of
    the Center For Watershed Protection and US Forest Service - Northeastern Area State & Private Forestry
    http://www.forestsforwatersheds.org/reduce-stormwater/


                                                            21
               The Value of Green Infrastructure for Urban Climate Adaptation


for erosion control.73 In Oakland, CA the continuous tree canopy is estimated to intercept
4 inches of rain, or 108,000 gallons of water, per acre in a typical year. 74 Trees can
reduce runoff in urban areas by up to 17%.75

In terms of mitigating UHI impacts, trees typically absorb 70 to 90% of sunlight in
summer and 20 to 90% in winter, with the biggest seasonal variation seen in deciduous
trees (versus evergreens) that lose their leaves annually. One study showed that trees can
reduce the maximum surface temperature of the roofs and walls of buildings by 11 to 25º
C. The estimated effect of new shade trees planted around houses resulted in annual
cooling energy savings of 1% per tree while annual heating energy use decreased by
almost 2% per tree.76 Direct energy savings from shading by trees and vegetation could
reduce carbon emissions in various U.S. metropolitan areas by roughly 1.5 to 5% due to
decreases in cooling energy use.77

A climate modeling study in Manchester, England found that adding 10% green cover
like grass and shrubs in high density areas would keep surface temperatures below
historical baseline levels, except under conditions of high CO2 emissions. In the model,
when green roofs were also added to high density areas, temperatures stayed below
baseline levels even under the high emissions scenarios. Conversely, the studies also
show that if green cover is left unaltered, temperatures are expected to increase about 3.3
to 3.8°C.78

In addition to these benefits, trees absorb and reduce various pollutants found in the
urban environment, including particulate matter (PM), nitrogen oxides (NOX), sulfur
dioxide (SO2), carbon monoxide (CO), and ground-level ozone (O3). One study
predicted that increasing the urban canopy of New York City by 10% could lower
ground-level ozone by about 3%. Another study estimated that one million additional
trees in a city could lower emissions of NOx by almost a quarter ton per day and
particulate matter by over one ton per day. A 2006 study estimated that urban trees in the
United States remove 784,000 tons of pollutant per year at an economic value of $3.8
billion. The study focused only on deposition of ground-level ozone, PM, NO2, SO2 and
CO. Although the estimated changes in local ambient air quality were modest, typically
less than 1%, the study noted that additional benefits would be gained if urban
temperature and energy impacts from trees and vegetation were also included.79




73
   EPA Heat Islands Compendium (October 2008): Trees and Vegetation
74
   Fact Sheet #4 Website
75
   “Benefits of Trees” Factsheet (website), Houston Area Urban Forestry Council <http://www.h-
gac.com/community/livable/forestry/documents/benefits_of_trees.pdf
76
   EPA Heat Islands Compendium (October 2008): Trees and Vegetation
77
   EPA Heat Islands Compendium (October 2008): Trees and Vegetation
78
   Adapting Cities For Climate Change: The Role Of The Green Infrastructure S.E. GILL, J.F. HANDLEY, A.R.
ENNOS And S. PAULEIT, Built Environment Vol. 33, No. 1 (2007)< http://www.fs.fed.us/ccrc/topics/urban-
forests/docs/Gill_Adapting_Cities.pdf>
79
   EPA Heat Islands Compendium (October 2008): Trees and Vegetation


                                                      22
               The Value of Green Infrastructure for Urban Climate Adaptation


Economic Costs and Benefits of Urban Forestry
The primary costs associated with planting and maintaining trees or other vegetation,
include purchasing seeds or saplings, planting, and routine maintenance such as pruning,
pest and disease control, and watering. Other costs of urban forestry include program
administration, lawsuits and liability, root damage, and tree stump removal. Generally,
however, the benefits of urban trees outweigh the costs. Costs to establish trees vary
depending on type of species, location, and climate zone. The city of Chicago estimates
that urban forestry costs $50 to $500 per tree to establish. A five-city study estimates an
annual maintenance cost of $15 to $65 per tree. Studies have shown that the net
economic benefits of mature urban trees range from $30 to $90 per year for each tree,
accounting for all of the benefits listed above. Cities can accrue a rate of return on each
tree of approximately $1.50 to $3.00 for every dollar invested.80

Many studies also show that trees and other vegetative landscaping can increase property
values. Studies have found general increases of about 3 to 10% in residential property
values associated with the presence of trees and vegetation on a property. Other studies
indicate increases from 2 to 37%.81 In areas with high median residential sales prices,
these property value increases are often among the largest categories of benefits for a
community.82 A study in Portland showed that trees added $8,870 to the sale prices of
residential properties, reducing time on market by 1.2 days.83 Trees in Portland, Oregon
generate approximately $13 million per year in property tax revenues by increasing real
estate values.84

Some communities have begun to achieve infrastructure cost savings by looking to the
ecosystem services provided by urban forestry when used in lieu of “grey” infrastructure
investments for managing stormwater. In 1997, New York City decided against
constructing a new water filtration plant that would have cost $6 billion to construct and
$300 million per year to operate. Instead, the city is spending far less–$1.5 billion over
10 years–to improve Catskill watershed forest protection. By securing the source of the
water, the forests will naturally filter and purify the drinking water at a significantly
reduced investment.85 A modeling study showed that Washington, DC could potentially
realize annual operational savings between $1.4 and $5.1 million per year from reduced
pumping and treatment costs by implementing additional urban forestry practices.86



80
   EPA Heat Islands Compendium (October 2008): Trees and Vegetation
81
   City Trees and Property Values, Kathleen Wolf (2007) University of Washington, Seattle <
http://www.cfr.washington.edu/research.envmind/Policy/Hedonics_Citations.pdf>
82
   EPA Heat Islands Compendium (October 2008): Trees and Vegetation
83
   CNT Multiple Benefits (April 2010)
84
   Haan Fawn Chau, Green Infrastructure for Los Angeles: Addressing Urban Runoff and Water Supply Through Low
Impact Development, City of Los Angeles (April 17, 2009)<http://www.ci.la.ca.us/san/wpd/Siteorg/program/Exec-
Summ-Grn-Infrastruct.pdf>
85
   Sandra L. Postel and Barton H. Thompson, Jr., “Watershed protection: Capturing the benefits of nature’s water
supply services” Natural Resources Forum 29 (2005) 98–108<
http://www.consrv.ca.gov/dlrp/watershedportal/Documents/Watershed%20ProtectnNat%20Res%20Forum05.pdf>
86
   “The Green Build-out Model: Quantifying the Stormwater Management Benefits of Trees and Green Roofs in
Washington, DC.” Casey Trees and LimnoTech. Under EPA Cooperative Agreement CP-83282101-0 (May 15, 2007)<
http://www.caseytrees.org/planning/greener-development/gbo/index.php>


                                                      23
                The Value of Green Infrastructure for Urban Climate Adaptation


   TABLE 5: Annual benefits of Washington’s street trees primarily result from
 increases in property value due to the presence of trees accounting for much of the
                   Aesthetic/Other benefit (Source: Casey Trees)

                                 Annual Economic Benefits of Street
                                 Trees (Washington, DC)
                                 Energy                  $1,308,778
                                 CO2                       $349,104
                                 Air Quality               $185,547
                                 Stormwater              $3,695,873
                                 Aesthetic/Other         $5,138,396
                                 Total:                 $10,677,697


Because tree maintenance can be a financial burden for private landowners, a tax
incentive for property owners to maintain the urban forest could encourage more
participation from community members.87 The Ontario Ministry of Natural Resources
provides a tax incentive to rural land owners with 10 acres or more of forest who agree to
follow a Managed Forest Plan for their property. Participating landowners pay only 25%
of the municipal tax rate for residential properties. A similar incentive for the
management of urban trees could be a very effective way to engage private property
owners in other communities.88


Economic and Climate Value of Trees

     Chicago–The structural value of the benefits from urban forestry in Chicago totals $2.3
     billion and the total carbon sequestration rate is 25,200 tons/year equivalent or a value of
     $14.8 million/year based on an estimated market value for carbon.89

     San Francisco–In the San Francisco Bay
     area, total annual benefits for the region were
     estimated at $5.1 billion, ranging from $103
     million in San Francisco County to $1.5
     billion in Santa Clara County. Property value
     enhancement accounted for 91% of total
     benefits, followed by energy (electricity and
     natural gas) at 6%, storm runoff at 2%. A 3%
     increase in canopy cover in the region was
     projected to result in added benefits of $475
     million, or $69 per capita.90                               Figure 7: New street trees in San Francisco



87
   Eva Ligeti, “Climate Change Adaptation Options for Toronto’s Urban Forest”(2007) Clean Air Partnership <
http://www.cleanairpartnership.org/pdf/climate_change_adaptation.pdf>
88
   Ligeti, Toronto’s Forests (2006) CAP
89
   Ligeti, Toronto’s Forests (2006) CAP


                                                        24
                  The Value of Green Infrastructure for Urban Climate Adaptation




  Importantly, urban forests provide co-benefits to climate mitigation efforts by acting as
  carbon sinks and lowering electricity demand for cooling.91 In 2005, total carbon storage
  in urban trees in the United States was approximately 700 million tons, with net
  sequestration estimated at around 24 million tons per year (88.5 million tons
  CO2equivalent). A 2006 study found that about 15,000 street trees in Charleston, SC,
  were responsible for an annual net reduction of over 1,500 tons of CO2 worth about $1.50
  per tree based on average carbon credit prices, for a total of about $2,250.92

  Trees in Atlanta have been calculated to provide $8 million worth of pollution removal
  value and store a total of 1.2 million tons of carbon.93 In Washington, D.C., the street
  trees provide over $10 million in annual carbon, air quality, stormwater, energy and
  property value benefits. The 1.9 million trees in the city sequester over 16,000 tons of
  carbon annually which has a value of about $300,000 based on an estimate of the market
  value of carbon.94 The table below illustrates the pollution reduction and monetary
  benefits that have been experienced by U.S. cities through implementing urban forestry
  programs with GHG emissions mitigation goals in mind.


  Table 6: Carbon and Pollution Storage and Monetary Value from Urban Forestry95

                                                                        Energy       Energy
                                            Carbon       Gross C          Use          Use         Polln./yr
                    Data                    Stored       Seq/yr        Avoided       Avoided       Removed        $/yr Polln.
                    Year       # Trees       (MT)         (MT)         (mBTU)        (MWH)           (T)          Removed
Chicago             2007      3,585,203     649,336        22,831        127,185        2,988            889       $6,398,200
                                             1,225,2
New York City        1996     5,211,839          28         38,358      630,615        23,579           1,997    $10,594,900
Philadelphia         1996     2,112,619     481,034         14,619      144,695        10,943             727     $3,934,100
San Francisco        2004       669,343     178,250          4,693     No Data       No Data              235     $1,280,000
Washington,
DC                   2004     1,927,846     474,417         14,649       194,133         7,924            489      $2,524,200




  90
    James R. Simpson and E. Gregory McPherson, San Francisco Bay Area State of the Urban Forest: Final Report;
  Center for Urban Forest Research, USDA Forest Service, Pacific Southwest Research Station (December 2007)<
  http://www.fs.fed.us/psw/programs/cufr/products/2/psw_cufr719_SFBay.pdf>
  91
   For purposes of this paper: “co-benefits” are specifically those that achieve both mitigation and adaptation
  goals simultaneously—while other benefits are considered “multiple”.
  92
     EPA Heat Islands Compendium (October 2008): Trees and Vegetation
  93
     Amy Morsch, “A Climate Change Vulnerability and Risk Assessment for the City of Atlanta, Georgia,” Thesis, Duke
  University (2009)< http://dukespace.lib.duke.edu/dspace/handle/10161/2157>
  94
     Quantified Benefits of using iTree, (iTree Streets (STRATUM) and iTree Eco (UFORE)) website, Casey Trees,
  Washington, DC (2010) <http://www.caseytrees.org/geographic/key-findings-data-resources/quantified-
  benefits/index.php>
  95
     Urban Forest Data website – City Lists, Northern Research Station, US Forest Service (2010)
  <http://nrs.fs.fed.us/data/urban/>


                                                         25
                          The Value of Green Infrastructure for Urban Climate Adaptation


            Wetlands: A Lesson Learned in the Benefits of Urban Forestry

            In the 1960s, urban planners began to recognize that wetlands buffer regional
            infrastructure and housing against flooding. More recently, wetlands began to be seen as
            an effective means to manage the more intense and frequent precipitation events expected
            under climate change conditions, including reducing peak flows and reducing the
            intensity of flood events in urban areas. In 1978, the Army Corps of Engineers began
            purchasing land and acquiring development easements to preserve wetlands in the
            Charles River Basin near Boston, Massachusetts. By 1983, 75% of wetlands in the basin,
            about 8,000 acres had achieved protected status at an estimated cost of $100 million
            ($618 million in today’s dollars). Without protection, the Corps estimated that 40% of all
            existing wetlands at the time would have been lost to development by 1990. The wetlands
            have protected downstream communities on numerous occasions in recent decades and
            they prevent an estimated $40 million in flood damages every year.

                                                                                In contrast, communities in
                                                                                neighboring basins without
                                                                                intact wetland systems have
                                                                                continued to suffer flood
                                                                                damages. In May of 2006,
                                                                                the community of Lawrence,
                                                                                Massachusetts received 8.7
                                                                                inches of rain over several
                                                                                days, resulting in an
                                                                                estimated $19 million in
                                                                                flood damages. At the same
                                                                                time, communities along the
                                                                                Charles River, including
                                                                                Boston and Cambridge,
                                                                                received 9 inches and
                                                                                suffered almost no flood
                                                                          damage. The protected
Figure 8: Wetlands naturally store and slowly release stormwater into streams
(Source: Greener Loudon)                                                  wetlands provide a wide
            range of other water quality, recreational and economic benefits as well. Tourists
            contribute over $4.5 million to the local economy. Properties adjacent to the protected
            wetlands have shown direct benefits to local residents through increased property values.
            In all, the Charles River wetland protection project has been a great benefit to the
            watershed.

            The wetland system is more cost effective than conventional alternatives in buffering
            communities against flooding. Building a wastewater treatment system using constructed
            wetlands costs about $5.00 per gallon of capacity compared to roughly $10.00 per gallon
            of capacity for a conventional advanced treatment facility, however, it should be noted
            that such treatment systems can be used in only limited circumstances usually associated
            with small communities with limited wastewater flows.



                                                            26
                The Value of Green Infrastructure for Urban Climate Adaptation


Wetlands in the US overall are estimated
to provide $23.2 billion in storm
protection services.96 In Pensacola Bay,
FL between 2001 and 2003, 15 acres of
coastal wetland created a cumulative
value for hurricane and storm protection
of $1.3 million through avoided damage
to roads. In 2008, 30 acres at another
location achieved $1.9 million in savings
from similar protections.97 In the
Charles River example, wetland
purchases and easements cost less than
$10 million and contribute over $95
million to the regional economy every      Figure 9: Wetlands also provide habitat for wildlife and
year, compared to a flood control dam      can act as moderate carbon sinks
which would have cost over $100 million and provided few, if any additional benefits.98
The use of a wetland system also helps communities to buffer against drought because
wetlands store and release water gradually, delaying the effects of dry periods.99




Managerial, Institutional and Market-based Approaches
to Climate Resilience
Besides implementing green infrastructure practices to withstand and accommodate
climate impacts and weather extremes, local governments can wield managerial,
institutional, and market incentives to lower climate risks and encourage adaptive
behavior, or at a minimum, to avoid maladaptations. These practices provide either
positive incentives (carrots) or sanctions (sticks), encouraging adaptation by rewarding
behavior change or punishing the lack thereof. As shown earlier, cities and counties can
reap higher net-benefits from implementing lower cost green infrastructure alternatives
with multiple co-benefits (green vs. grey infrastructure). They can pay property owners
to change behavior, for example, by providing downspout disconnection payments as was
done in Portland, or waiving storm-water fees for greater site permeability as was the
case in Washington, DC. In doing so, cities may gain indirect benefits from lower
96
   Robert Costanza et al, “The Value of Coastal Wetlands for Hurricane Protection,” Ambio, Vol. 37, No. 4 (June 2008)
< http://www.uvm.edu/giee/publications/Costanza%20et%20al.%20Ambio%20hurricane%202008.pdf>
97
   Amy Baldwin, Submerged Resources in the Face of a Changing Climate: Living Shorelines as an Adaptation
Strategy, Submerged Lands Seminar Series, Florida DEP (September 23, 2010)<
http://www.submergedlandsconference.com/sessions.php><http://www.submergedlandsconference.com/presentations/
0923/Baldwin.pdf><http://www.dep.state.fl.us/northwest/Ecosys/section/greenshores.htm>
98
   Natural Security website: Charles River, Massachusetts Wetlands as Flood Protection, American Rivers
(2009)<http://www.americanrivers.org/our-work/global-warming-and-rivers/infrastructure/natural-security-charles-
river.html>
99
   Natural Security website: Clayton County, Georgia, Withstanding Drought with Wetlands and Water Reuse,
American Rivers (2009)<http://www.americanrivers.org/our-work/global-warming-and-rivers/infrastructure/natural-
security-clayton-county.html>


                                                         27
                The Value of Green Infrastructure for Urban Climate Adaptation


insurance premiums and increased tax revenue from the higher property values that green
infrastructure can produce. They may also enjoy the benefits of greater competiveness
due to the adaptation jobs that may be created by building green infrastructure. Savings
from avoided public health or disaster impacts, a more reliable water supply, faster
economic recovery after disasters, energy savings, and carbon storage are other benefits
that cities can expect when implementing green infrastructure measures.


Managerial Approaches
Green management practices may include planning, urban design, and smart growth
approaches that incorporate green infrastructure into the urban landscape. Examples are
higher density housing that accommodates green open spaces, large-scale urban forestry
projects in neighborhoods or in green-belts around cities, or coastal wetlands buffering
against hurricane storm surges or river flooding. Accommodating climate impacts is
another adaptation strategy that may be implemented by decision makers, with the goal of
intentionally absorbing impacts by designing communities in ways that aim to minimize
damage rather than preventing it.100 Examples include local building codes in flood
zones that mandate raising buildings or bridges above current and future flood-levels or
requiring that first floors are “floodable”. 101

Some municipalities are intentionally designing roads as flood canals to channel water
away from downtowns to increase their flood resilience, or establishing park and
recreation land in town-centers as “green” floodways for when local rivers overtop their
banks (for example: Grand Forks, South Dakota). The Dutch are beginning to designate
parts of urban and rural areas of the Netherlands that are floodable in anticipation of
future climate change, including building houses that can float in floods or flood canals
through downtown Rotterdam.102 Retreating from floodplains that are frequently
inundated or coastal areas threatened by sea-level rises is another strategy.

Timing of expenditures is another management strategy that can be used because
adaptation practices can be implemented as needed. For example, building or raising
dykes can be staged until sea-level actually rises, however, planning, preparation,
permitting, land acquisition, and appropriating funding can be done in advance of the
need to construct. The key element of this kind of strategy is to plan and prepare in the
present so that actions can be taken in the future as needed faster and at a lower cost than
reactionary measures. Decision-makers can allocate funds in unconventional ways to
ensure better climate adaptation. For instance, recognizing the water management
benefits of green roofs, the Toronto City Council allocated $200,000 from Toronto’s

100
    Accommodation strategies—in comparison to retreating from a floodplain, or building a flood-barrier to prevent any
damages
101
    Successful adaptation to climate change across scales W. Neil Adger, Nigel W. Arnella, Emma L. Tompkins, Global
Environmental Change 15 (2005) 77–86<
http://research.fit.edu/sealevelriselibrary/documents/doc_mgr/422/UK_Successful_Adaptation_to_CC_-
_Adger_et_al_2005.pdf>
102
    (Adger et al (2005));(also: “Floating houses built to survive Netherlands floods: Anticipating more climate change,
architects see another way to go” (November 09, 2005) By Peter Edidin, New York Times
<shttp://articles.sfgate.com/2005-11-09/home-and-garden/17399121_1_flood-zones-dutch-floating>)


                                                          28
                The Value of Green Infrastructure for Urban Climate Adaptation


water budget to encourage green roof construction in 2009. Subsidies were made
available to property owners of $10 per square meter, up to a maximum of $20,000, for
new and retrofit green roofs.

Finally, there also is a critical need for local decision makers to be provided with climate
change information relating to temperature change, rainfall frequency and intensity
changes, floodplain adjustments, sea level rise, and storm surge changes to use to support
decisions on green infrastructure implementation and other adaptive actions.


King County: A Prime Example of Managerial Adaptation

King County Flood Control District was reformed to merge multiple flood management
zones into a single county entity for funding and policy oversight for projects and
programs—in part in anticipation of increased stormwater flows from climate change.
King County floodplains have been declared federal flood disaster areas 10 times since
1990 with floods in 2006 costing $33 million in damages. The primary goal of
redistricting was to ensure $345 million of funding was available for maintenance,
repairs, and upgrades of flood protection infrastructure such as levees. The district’s key
strategies and objectives related to climate adaptation and green infrastructural include:

      •   Reducing risk by permanently removing flood, erosion, and landslide prone
          residential structures
      •   Reducing risk exposure by elevating structures and strengthening flood facilities
      •   Improving floodwater conveyance and capacity by reconnecting rivers to their
          floodplain
      •   Providing safe access to homes and businesses by protecting key transportation
          routes
      •   Natural resource protection actions include sediment and erosion control, stream
          corridor restoration, watershed management, forest and vegetation management,
          and wetland restoration and preservation103




Institutional Approaches
Insurance, finance, laws, and regulations are institutional mechanisms that can be used to
incentivize adaptive behavior. Some of useful institutional mechanisms include:

      •   Local zoning of land-use ( such as density requirements for smart growth or
          rolling easements to address sea-level rise),
103
   King County Flood Control District- FAQ (November 2008)<
http://www.kingcountyfloodcontrol.org/pdfs/kcflood_faqs.pdf>; King County Flood Control District Annual Report
2008<http://your.kingcounty.gov/dnrp/library/water-and-land/flooding/kcfzcd/crs-recertification/flood-control-district-
2008-annual-report.pdf; King County Flood Control District, Hazard Mitigation Plan (March 2010)<
http://your.kingcounty.gov/dnrp/library/water-and-land/flooding/local-hazard-mitigation-plan-
update/KCFCD_HazardPlan_Mar2010.pdf>


                                                          29
                  The Value of Green Infrastructure for Urban Climate Adaptation


        •   Building codes, green infrastructure design standards,
        •   Landscape ordinances, or
        •   Federal, state, and local environmental statutes.

For example, Chicago uses a regulatory disincentive to encourage developers to include
more trees in their site designs. If a construction design stipulates that a tree will be
removed, the tree is assessed and assigned a dollar value which the developer must pay to
the City. This measure has been encouraging developers to re-visit their designs and
preserve existing trees.

Insurance also helps to hedge against climate risks. To define communities eligible for
insurance against flooding, the National Flood Insurance Program under the Federal
Emergency Management Agency (FEMA) maps flood elevations for 1 in 100 year flood
frequencies. However, the program does not currently accommodate climate change
projections for increased flood frequency and intensity in determining insurability. The
current mapping program may even be providing incentives for property owners to build
in risky areas through the use of obsolete maps and the tolerance of repeated claims in
frequently flooded locations.104 Additionally, although FEMA provides Pre-Disaster
Mitigation funding to eligible communities for assessing, planning, and preparing in
advance for disasters, climate change is not yet a hazard criteria.

Making the appropriate changes to include climate impacts in how insurance programs
assess risks could have a large effect on adaptive behavior. A study in Saskatchewan,
Canada in 2008 showed that using zoning approaches to address climate change impacts
can be more cost-effective than conventional grey infrastructure methods. This climate
and economic modeling study compared zoning methods to hard infrastructure
approaches in their ability to avoid cost impacts from climate change-induced flooding
over the next 25 years. Building more flood infrastructure was found to save an
estimated $10 million in avoided flood damages, while rezoning alone would save $155
million, over 15 times more.105 What this section also highlights is that federal funding
of actions in local areas should be tied to policies and measures that account for climate
change risks and federal measures should be adapted to account for these risks.


Market Mechanisms
Market mechanisms shift the cost of implementing green infrastructure in positive
directions, increasing the feasibility of implementation. As discussed throughout this
paper, local governments can reap financial benefits from green infrastructure by using
cheaper green alternatives or avoiding costs of future climate damage. They can also
provide funding directly to property owners for on site implementation. For example,
104
      Legally, the program defines flood zones using historic climate data applied to current conditions
105
  Christensen, Paul N., Gordon A. Sparks, and Harvey Hill (2008) “Adapting to Climate Extreme Events Risks
across Canada’s Agricultural Economic Landscape: An Integrated Pilot Study of Watershed Infrastructure
System Adaptation.” Climate Change Impact and Adaptation Program. Natural Resources Canada Project No.
A1473. Prepared for Natural Resources Canada by Department of Civil and Geological Engineering, University of
Saskatchewan, Saskatoon, SK; Prairie Farm Rehabilitation Administration; Agriculture and Agri-Food Canada <
http://www.policyresearch.gc.ca/page.asp?pagenm=2010-0041_09>


                                                        30
                 The Value of Green Infrastructure for Urban Climate Adaptation


California initiated the Cool Savings Program which provided rebates to building owners
for installing roofing materials with high solar reflectivity and low thermal absorption.
The California Energy Commission paid incentives of 15 to 25 cents per square foot of
eligible roofing area. The program was so successful that California revised its Title 24 to
make cool roofs on certain new or renovated buildings mandatory starting in 2005.

In the future, new mortgage products imitating PACE loans may incorporate the costs of
adaptation into private property transactions. 106 Noted above, tax credits for green
infrastructure implementation, reduced storm-water fees rewarding greater site
permeability, or rebates for downspout disconnection are just a few examples of how to
change price incentives by making some behaviors cheaper or more expensive. For
example, starting in 2007, New York City aimed to support the installation of extensive
green roofs by enacting a property tax abatement to offset 35% of the installation cost of
a green roof. Keeping discount rates low also makes investing in green infrastructure that
has longer-term benefits more valuable. As noted earlier, demonstrated increases in
property values from green-infrastructure raising tax revenue, or lowering insurance
premiums from greater site resilience also creates market incentives.




Conclusions: Implications for Policy, Research and
Technical Assistance
Asking the Resilience Question
Green infrastructure is a means for simultaneously advancing environmental
sustainability, smart growth, and now climate adaptation goals in urban settings with a
goal of creating more resilient metropolitan communities. Although definitions of these
concepts are at times vague and not entirely complementary they do overlap to a
significant extent.107 Sustainable development seeks goals of environmental protection,
economic viability, and long-term resource continuity along with equity and social justice
particularly for vulnerable populations. Smart growth uses the tools of planning and
urban design to achieve resource efficiencies, building density, mixed land-uses, open
space, public transit oriented development, and enhanced quality of life. More recently,
climate adaptation policies and practices have sought to build the capacity of local
communities and decision makers to better assess and manage risks, impacts, and
opportunities from irreversible climate change and extreme weather (floods, droughts,
wildfire, sea-level rise, and public health threats, etc.). Adaptation to climate change also
is seen as having ecological, economic, and social dimensions.108



106
  PACE: Property Assessed Clean Energy allows a local government to provide loans to homeowners for renewable
energy and efficiency retrofits paying back via tax bills. However, PACE currently has been defined by the Federal
government as an illegal lien on houses so the future of this mechanism is in question.
107
      Intergovernmental Panel on Climate Change (IPCC), 4th Assessment Report (2007): WG II Adaptation
108
       IPCC, AR4 (2007)


                                                        31
                    The Value of Green Infrastructure for Urban Climate Adaptation


At the intersection of these three concepts is a desire for more resilient communities that
are less vulnerable to natural and human induced hazards and disasters (See Figure 10).
Generally, resilience means that they can better withstand, cope with, manage, and
rapidly recover their stability after a variety of crises. However, there is considerable
debate about what it means to achieve a resilient community in practice (operationally).
For example, stability may not be a truly resilient trait if vulnerabilities are perpetuated in
recovery to an original state (e.g., post-flood disaster rebuilding in a frequently inundated
floodplain).


                              Sustainability                                          Climate Adaptation
                              --Equity                                                  *Manage Climate
                              --Environment                    Sustainability           Risks & Impacts
                              --Economy                                                 --Flood
                              --Social Justice &              New     &   Framing       --Heat
                              Capital                                                   --Fire
                              --Long-term                        Adaptation             --Drought
                              Resource                        RESILIENCE
                              Continuity                       --Climate Adaptation
                              --Green                          --Sustainability
                              Infrastructure                   --Smart Growth
                                                                                                      Emerging Framing
                                                              *Why & How
                                                              --avoid & manage
                     Old Framing
                                                              climate impacts and
                                          Sustainability                               Smart Growth
                                                              recover quickly
                                               &              at least cost                &
                                                              NEW FRAMING
                                          Smart Growth                                  Adaptation
                Paper will                Established
                                          Framing                                     New Framing
                focus on the
                intersection of                            Smart Growth
                “new framings”                             --Resource Efficiency (least cost)
                *Covers Multiple Scales     Old Framing    --Design                                    *Covers Multiple
                --Building                                 --Planning                                  Benefits & Best
                --Site                                     --Lower GHG                                 Practices
                --Neighborhood                             --Quality of Life                           *Plus Other
                --City                                     --Rationalized Transportation               Incentives
                --Region


Figure 10: The Intersection of Sustainability, Smart Growth and Adaptation



Diversity, flexibility, sustainability, adaptability, self-organization, and the ability to
evolve and learn are seen as key system attributes of community resilience as long as
they do not lead to mal-adaptation in the process.109 However, resilience generally is
thought of in more reactive terms—akin to “autonomous adaptation” that responds as
conditions change. In the face of climate change, adaptive capacity is seen as
encompassing resilience as it more comprehensively focuses on planning, preparing, and
implementing adaptive solutions drawing on a wide variety of technological, managerial,
institutional (social), and market capabilities.110 “Asking the resilience question”—
means that local planning and building decisions need to incorporate how to prepare for
and manage impacts from climate change and weather extremes—essentially
“mainstreaming” resilience by enhancing adaptive capacity.


109
      Klein, Resilience (2003)
110
      Klein, Resilience (2003)


                                                                 32
               The Value of Green Infrastructure for Urban Climate Adaptation



Delivering Adaptive Solutions through Climate Extension Services
Although local governments and communities are using green infrastructure to achieve a
variety of environmental and economic goals, including resilience to climate change,
application of green infrastructure solutions are not yet widespread as adaptation best
practices. Many communities either are unaware of the benefits of green infrastructure to
begin with or believe it’s more expensive or difficult to implement than traditional grey
approaches. Meanwhile, communities that have embraced green infrastructure may not
have connected it with adapting to climate change, or if they have, they may not possess
the necessary capacity, know-how, or resources to plan and implement solutions. One
solution to these barriers of awareness, willingness, and capacity is climate extension.

Climate extension would be a means to customize and deliver adaptation information and
to provide technical assistance and capacity to meet specific local adaptation needs.
Practical advice connecting green infrastructure with climate adaptation could be brought
to bear from university, non-profit, or federal and state government “climate extension
specialists” embedded in local communities. The most important information that
climate extension specialist could provide would be timely and up to date forecasts and
information on likely climate change impacts in the local urban area. They also could
provide technical assistance to both local governments and property owners on green
infrastructure practices highlighted in this report including: installing green roofs to
mitigate urban heat island effects and manage storm-water, changes to building codes
encouraging green infrastructure practices, managing urban forestry operations, and
establishing green alley, downspout disconnection, and water conservation incentive
programs.

Extension specialists could help city managers make the case to elected officials and
citizens about the value and multiple benefits of green infrastructure in the context of
climate change adaptation. Organizations, such as, Casey Trees, the Center for
Watershed Protection, the Center for Neighborhood Technology, American Rivers, and
ICLEI Local Governments for Sustainability are beginning to fulfill climate extension
roles. Universities in Arizona, Florida, Massachusetts, and Oregon have hired climate
extension specialists to work with farmers, land and resource managers, and urban
decision makers. NOAA’s National Sea Grant Program is working with states on
piloting climate extension in coastal communities.111 Several CCAP Urban Leaders
partners have made clear connections between green infrastructure and climate adaptation
in their city management and outreach programs including Chicago, Miami-Dade
County, New York City and Toronto providing extension to their own citizens




111
   NOAA Sea Grant Initiates $1.2 Million Community Climate Change Adaptation Initiative:
http://www.noaanews.noaa.gov/stories2010/20100909_seagrant.html


                                                      33
               The Value of Green Infrastructure for Urban Climate Adaptation


Closing Thoughts on Green Infrastructure and Resilience
This report provides evidence of the value of green infrastructure for local climate
adaptation based on significant net benefits and successful local action. In providing
comparable cost, performance, and benefits data across a selection of green infrastructure
practices the report avoids equating each practice as a solution to a single climate related
problem but rather shows that a mix of approaches is best. For example, white roofs are
often promoted as a panacea to reducing urban heat island effects while ignoring the
value of vegetated roofs to both lower temperature and to manage storm runoff at
comparable net benefit (even at higher initial investment). Instead, this report encourages
consideration of the multiple benefits of single green infrastructure solutions, the trade-
off among solutions to achieve multiple benefits, and how a combination of solutions
may lead to the highest net climate adaptation benefits depending on local needs,
capacities, and resources. For example, a building with a combination vegetated, white,
and blue roof, surrounded by green alleys incentivized under a downspout disconnect
program, and encouraged by a permeable pavement ordinance, shaded by street trees, and
buffered from floods by local wetlands, not only receives multiple net-benefits from
green infrastructure but de facto is more adapted to and mitigates climate change. If all
public and private property owners in a neighborhood, city, or county simultaneously
implement these practices the result is greater overall climate resilience across a region.

Interest in green infrastructure continues to grow with recognition from federal, state, and
local governments that practices can be used to solve multiple environmental problems--
complimenting more traditional infrastructure solutions. The connection to climate
adaptation is emerging—in some cases explicitly. Urban Leaders partners Chicago, New
York City, Toronto, Miami-Dade and King Counties are all implementing green
infrastructure as an adaptation strategy. American Rivers and New York City have made
clear linkages between storm-water, river basin management, climate adaptation, and
community resilience in local urban planning. At the federal level, Dr. Steven Chu, the
Secretary of Energy, promotes white roofs as a means to lower global and urban
temperatures as well as energy used for cooling—even if he does not frame it as climate
adaptation.

National policies on green infrastructure and climate adaptation are beginning to emerge.
In July 2009, Senators Tom Udall and Sheldon Whitehouse introduced S 3561 ‘The
Green Infrastructure for Clean Water Act of 2010’ finding that green infrastructure can
ameliorate the impacts of climate change on water resources. In October 2010, the White
House Climate Change Adaptation Task Force made recommendations to President
Obama for how Federal Agency policies and programs can better prepare the United
States to respond to the impacts of climate change.112 In the report, Joyce Coffee, Urban
Leader partner from Chicago is quoted: “The Federal Government should use the
precautionary principle to encourage cities to plan for greater uncertainty and variability
when building green and grey infrastructure by asking respondents to describe how their
planned projects adapt to climate change.” Later in the report, The Nature Conservancy

112
 White House Climate Change Adaptation Task Force
www.whitehouse.gov/administration/eop/ceq/initiatives/adaptation; Final Report:
www.whitehouse.gov/sites/default/files/microsites/ceq/Interagency-Climate-Change-Adaptation-Progress-Report.pdf


                                                       34
            The Value of Green Infrastructure for Urban Climate Adaptation


notes: “While certain hard infrastructure responses to climate change will be needed, it is
clear that effective long term adaptation to climate change will depend on reducing the
vulnerability and increasing the resilience of ecosystems and their essential services.”
Although these references are encouraging, connecting green infrastructure and climate
adaptation in national policies in support of local resilience will be an on-going policy
challenge.

Asking the Resilience Question is another way of emphasizing the continuing importance
of mainstreaming resilience into the decisions of elected leaders, local managers,
businesses, and citizens. Evidence from this report shows that a combination of green
infrastructure practices at the intersection of sustainability, smart growth, and climate
adaptation create strategies producing the highest net-benefits to individuals and society
as a whole. Ultimately, the net-value of enhanced social, environmental, and economic
resilience from green-infrastructure will be at the core of resilient communities in a
climate changed future.




                                            35
             The Value of Green Infrastructure for Urban Climate Adaptation



APPENDIX: EXAMPLES OF COMPREHENSIVE GREEN
INFRASTRUCTURE STRATEGIES
Depending on circumstances and motivations, CCAP Urban Leaders partners and other
pioneering communities have embraced the application of green infrastructure and
technologies as a means to prepare for and adapt to climate impacts and as a path to
environmental sustainability. Often green approaches are combined with modifications
to other traditional “hard” infrastructures (e.g., fixing, expanding, or redesigning storm-
sewers and streets, building storm-water storage tunnels, etc.). As discussed throughout
this report, cities have incentivized green infrastructure projects by:

 1) Showing evidence of upfront or life-cycle cost savings when compared to alternatives
for both public and private projects,

 2) Providing direct financial incentives to property owners for green infrastructure
installation,

3) Instituting laws, regulations, and local ordinances requiring implementation of green
infrastructure on private property, or

4) Mandating that public projects incorporate green infrastructure to demonstrate
viability and value (e.g., street tree planting, green modifications to roads, green-roofs on
public buildings).

The following are some comprehensive examples of green infrastructure investments in
urban regions of the United States to illustrate how communities are combining the
practices discussed above to achieve the greatest economic and environmental benefits.


CHICAGO
Chicago’s Green Urban Design (GUD) Plan was launched as a partnership among City
agencies, nonprofits, and the private sector to help to better manage flooding (and also heat
impacts. Rainfall filtration and capture is a key goal using permeable pavements, rooftop
and surface rain gardens, and green alleys. In 2007, 30 green alleys with permeable
pavement and high-reflectivity concrete had been installed, along with over 200 catch-
basins across the city. Green alley design also encouraged homeowner involvement in
disconnecting of rain-gutter downspouts from the sewer system, addition of rain-barrels to
capture rooftop runoff, and backup power supplies to sump pumps to prevent basement
flooding. The goal is to slow the rate of storm-water runoff onsite to prevent localized
flooding and to support the capacity of aging infrastructure to handle extreme precipitation
events.

Additionally, over 775 miles of combined storm and sewer pipes were modeled to evaluate
surface and basement flooding problem spots and to recommend cost effective solutions—


                                              1
                     The Value of Green Infrastructure for Urban Climate Adaptation


      including green infrastructure. In the area of water conservation, a five-year, $620 million
      capital improvement project is saving an estimated 160 million gallons of water a day by
      reducing leaks. Because energy is used to pump, filter, distribute, and treat water for
      discharge, water conservation will help to decrease the 190,266 MWh of electricity the city
      consumes annually to pump and treat its water, thereby reducing GHG emissions. 113




A before and after view of a Chicago alley. The before picture shows how impermeable traditional
pavements excacerbate flooding. The green ally improvements, shown on the left, eliminate standing
water problems after rain events.




      PORTLAND 114
      In Portland, storm-water runoff conveys a variety of contaminants from properties and
      roadways into local sewers where it combines with raw sewage producing sewer
      overflows into local streams and rivers. In 1991, to solve its storm-water and sewage
      problems, Portland developed a $1.4 billion plan to build new sewer lines and large pipes
      that can store sewage during storms. Portland land surfaces are about 50% impermeable
      with 25% attributed to streets and 40% to rooftops. In 2004, Portland experienced 50
      overflow events discharging 2.8 million gallons of polluted water into area waterways.
      Consequently, the city more recently has provided economic incentives for homeowners
      to install green roofs and disconnect downspouts. They have also redesigned streets with
      rain gardens and other landscaping features that mimic natural systems to reduce the
      amount of storm-water that enters sewers limiting potential sewer overflows. In 2004,
      the city invested $3 million in green infrastructure projects.

      113
          Chicago Green Urban Design website and documents:
      http://www.cityofchicago.org/content/dam/city/depts/zlup/Sustainable_Development/Publications/Green_Urban_Desig
      n/GUD_booklet.pdf; http://greeningthecity.wordpress.com/chicagos-green-renaissance/;
      http://www.cityofchicago.org/city/en/depts/zlup/supp_info/green_urban_design.html
      114
          Natural Security website: Portland, Oregon: Integrating Gray and Green Infrastructure. American Rivers
      <http://www.americanrivers.org/our-work/global-warming-and-rivers/infrastructure/natural-security-portland.html>
      (Rooftops to Rivers (2006) NRDC, Portland Case)


                                                             2
                The Value of Green Infrastructure for Urban Climate Adaptation



Buildings owners also were given zoning incentives for installing green roofs as well as
requiring on-site storm-water management. In 2006, the city instituted storm-water
management fee discounts of up to 35% for green infrastructure installation. In 2008, the
city expanded it’s Grey to Green initiative with a plan to invest $50 million in green
infrastructure over five years. The goal was to increase the number of green streets,
ecological roofs, and trees while protecting undeveloped open spaces and restoring native
vegetation. A Downspout Disconnection Program at the time paid 45,000 households
$53 for each downspout disconnected, a total of 60,000, removing 1.5 billion gallons of
sto rm-water per year.115 Green Street
projects retain and infiltrate about 43
million gallons per year and have the
potential to manage nearly 8 billion
gallons, or 40% of Portland’s runoff
annually. A single green infrastructure
sewer rehabilitation project saved $63
million not counting other benefits
associated with green practices (e.g.,
clean air, groundwater recharge, etc).

Overall, Portland invested $8 million
in green infrastructure to save $250
million in hard infrastructure costs        Among its incentives, Portland provides up to
including reducing the size of sewer        100% discount on stormwater management fees to
pipes needed to capture the projected       households that disconnect their downspouts
combined wastewater and stormwater
flows from 33 to 26 inches.116 Valuation of green infrastructure is calculated via
comparison to “hard” alternatives, value of avoided damages, or market preferences that
enhance value (e.g. property value).117 Portland is implementing these green practices in
anticipation of more frequent and extreme precipitation from climate change. In their
view, green infrastructure practices can be readily spread across property owners or
integrated into existing city projects as needed to increase storm-water management
capacity in a manner that is cost-effective, flexible, and scalable as climate conditions
vary or change in the future—an example of increased resilience.


MILWAUKEE
Despite substantial investments in gray infrastructure to control CSOs (e.g., $2.4B for a
stormwater storage tunnel), Milwaukee also has invested in green-infrastructure to
enhance effective storage capacity. From 2003 to 2004, Milwaukee spent about $900,000
on green infrastructure. The city spent $170,000 on downspout disconnections, rain
barrels, and 60 rain-gardens to control runoff. It installed a $380,000, twenty thousand
square foot green roof on a local housing project that will retain 85% of runoff with the

115
    Haan Fawn Chau, Green Infrastructure for Los Angeles (April 2009)
116
    House Committee on Transportation and Infrastructure, Hearing, February 2009
117
    CNT Multiple Benefits (April 2010)


                                                         3
                The Value of Green Infrastructure for Urban Climate Adaptation


remaining 15% redirected to rain-gardens and retention basins for onsite irrigation. An
additional $300,000 was spent on four other green roof projects.

Modeling estimated that the neighborhoods installing green infrastructure could
experience a 31 to 37% reduction in storm-water flow to waste-water plants with a 5 to
36% reduction in peak flows and a 14 to 38% reduction in CSO volume. Green
infrastructure practices implemented in commercial areas was anticipated to reduce CSO
volume by 22 to 36%. Milwaukee plans to spend an additional $11 million on green
infrastructure through 2014.118

In May 2010, the Milwaukee Metropolitan Sewerage District awarded $3.7 million in
green infrastructure grants to 14 groups, including American Rivers. The grants will
support a range of green roof projects, from a small project in Mequon to a massive
remake of the roof of the Golda Meir Library at UW Milwaukee to an education center
focused on best management practices in green infrastructure. The latter facility will
feature over 7,500 square feet of permeable pavement, 4,000 square feet of green roof,
1,100 square feet of bio-swales and rain gardens and two 1,000 gallon rain harvesters and
rain barrels.119



PHILADELPHIA
Since 2006, Philadelphia has been using policies and demonstration projects throughout
the city to help promote green infrastructure in planning and development drastically
reducing CSOs, improving compliance with federal water regulations, and saving
approximately $170 million. Covering more than one square mile of the city green
infrastructure includes, green roofs, rain gardens, vegetated swales & landscaping, porous
pavement, downspout disconnection, rain barrels, & cisterns. To manage stormwater
runoff more efficiently, the Philadelphia is institutionalizing green infrastructure through
demonstration and restoration projects, a new stormwater fee system, and stringent
stormwater regulations for all new construction and redevelopment.

A study for the Philadelphia compared a “green” low impact development option with a
traditional “gray” sewer approach for the same level of runoff control performance. The
goal was to reduce combined sewer overflows while maximizing the net present value of
benefits. The green infrastructure option compared favorably in terms of net present
value, resulting in $2.8 billion in benefits compared to only $120 million for the gray
infrastructure option–more than a twenty-fold difference.121


118
   Rooftops to Rivers (2006) NRDC, Milwaukee Case
119
   American Rivers and 13 Milwaukee Groups Receive $3.7 Million in Green Infrastructure Grants (May 10,
2010)<http://www.americanrivers.org/newsroom/press-releases/2010/american-rivers-and-13-milwaukee-groups-
receive-grants.html>
121
  Robert S. Raucher, “A Triple Bottom Line Assessment of Traditional and Green Infrastructure Options for
Controlling CSO Events in Philadelphia's Watersheds Final Report,” Stratus Consulting, August 24, 2009; Table S.2.




                                                         4
                The Value of Green Infrastructure for Urban Climate Adaptation


In addition, Philadelphia has used a number of ordinances to accelerate green
infrastructure investments. The city is revising its stormwater billing system to create a
more equitable fee structure that more closely reflects the costs of managing stormwater
from each property. Rather than charge a single flat rate for all metered customers, new
fees will be determined by calculating the amount of impervious cover on a given
property. In this way, stormwater fees will reach customers accounting for significant
impervious surfaces. This reallocation of stormwater charges to large non-residential
customers will be implemented over a four-year period beginning in fiscal year 2009.
The new ordinance will also provide a financial incentive for customers to retrofit
properties with green infrastructure installments that reduce impervious cover.

In 2006, Philadelphia revised and streamlined its entire development review process so
that all developments resulting in more than 15,000 square feet of earth disturbance must
submit stormwater plans early in the permitting process. The ordinance also exempts
projects from the standard Channel Protection and Flood Control Requirements if they
can reduce directly connected impervious area (DCIA) by at least 20% encouraging in-
fill development and application of green infrastructure practices.122



NEW YORK CITY
In September 2010, New York City released it’s “NYC Green Infrastructure Plan: A
Sustainable Strategy for Clean Waterways” (Department of Environmental Protection).123
Toward advancing PlaNYC, the Green Infrastructure Plan seeks to achieve multiple
benefits including climate adaptation via a: “multi-pronged sustainability effort that will
reduce the urban heat island effect, enhance
recreational opportunities, improve quality-of-life,
restore ecosystems, improve air quality, save energy,
and mitigate and adapt to climate change. These goals,
as well as improved water quality, are substantially
advanced by green infrastructure in ways that
traditional grey infrastructure cannot match.

EPA has stated that the use of green infrastructure is an
“effective response to a variety of environmental
challenges that is cost-effective, sustainable, and
provides multiple desirable environmental outcomes”.
The Green Infrastructure Plan aims to reduce the City’s
sewer management costs by $2.4 billion over 20 years.
One of the main goals of the Plan is to cost effectively
reduce CSOs from 10% of the impervious surfaces in
the City. It is estimated that CSO volumes by 2030 will
122
    EPA Managing Wet Weather with Green Infrastructure website: Philadelphia Case
<http://cfpub.epa.gov/npdes/greeninfrastructure/gicasestudies_specific.cfm?case_id=62>
123
    NYC Green Infrastructure Plan (2010)
http://www.nyc.gov/html/dep/html/stormwater/nyc_green_infrastructure_plan.shtml




                                                         5
             The Value of Green Infrastructure for Urban Climate Adaptation


be 2 billion gallons less using green practices than building grey infrastructure.

The cost to implement the overall Plan is $1.5 billion less then grey, with green storm-
water capture alone saving $1billion at a cost per gallon of about $.15 less. Sustainability
benefits over the 20 year life of the project range from $139 - $418 million depending on
measures implemented. The plan estimates that “every fully vegetated acre of green
infrastructure would provide total annual benefits of $8,522 in reduced energy demand,
$166 in reduced CO2 emissions, $1,044 in improved air quality, and $4,725 in increased
property value.”




                                              6
      Center for Clean Air Policy
   750 First Street, NE • Suite 940
       Washington, DC 20002
Tel: 202.408.9260 • Fax: 202.408.8896

          www.ccap.org

				
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